Janna's Friends in Bot Lane:
Categories of ADC: Poke, All-in, M6(Monster @ 6), P/A (Passive/Aggressive), LGM (Late Game Monster), MFE (Must get Fed Early), NTE (No True Escapes)
Poke, M6, P/A, LGM, NTE - Ashe likes passive/aggressive lanes, and Janna is happy to comply. Janna can peal for Ashe in lane and synergizes well with Ashe's perma-slows and the Arrow of Truth. Also, if Janna starts E first, Ashe's level 1 crit + Volley poke becomes all that much more powerful. This is a very good lane to gank because of Ashe's amazing CC and damage output. Once Ashe hit 6, this lane becomes VERY scary.
Poke, P/A - Caitlyn loves abusing her stupid range when farming and poking. Janna and Caitlyn can peal for eachother (Janna tornadoes and Zephyrs, Caitlyn traps and nets). Janna can really help Caitlyn abuse her passive and stupid range by shielding Caitlyn when she get's a Headshot proc. It makes the poke stronger and protects Caitlyn from being poked.
All-in, P/A - Corki is the most annoying lane other than Tristana with Janna. He will NEVER die EVER... if you play it right. This lane can be passive or aggressive because of Corki's Valkyrie and Janna's skill set. The enemy can engage on Corki all they want, but they'll have a tornado in their face and Corki's fire bombs in front of them. This lane is also good to gank because of Corki and Janna's mobility.
Poke, All-in, M6, MFE->LGM, NTE - Okay I've had this lane before and it is amazing. Draven is a very poke then all-in oriented ADC, similar to Ezreal, but has shorter range and harder poke. Janna's shield is just ridiculous with his Spinning Axes and her entire kit compliments him well. They can slow down enemies just to speed themselves up and then keep them around for quite a long time until they just die.
Poke, All-in, P/A, LGM - Janna and Ezreal can be a very strong poke lane with Ezreal's Mystic Shot synergizing well with Janna's shields, while if they engage on their enemies, Ezreal's high mobility and Janna's high utility can synergize well. Her tornado can ensure Ezreal's Mystic Shot + Essence Flux hits, while Ezreal's snipes can become even stronger with Janna's AD buff. Ezreal is still better with Taric though.
All-in - Firstly, Graves will always be better with Taric on the grounds that Graves has high burst. However, with Janna, he can still do well. He will still have good burst because of Janna's AD steroid, but not as much because she doesn't have armor shred like Taric does. However, Janna makes the lane much safer, even without a heal. This is a great lane to gank because Graves can cut off their vision while Janna CC's them.
All-in, M6, P/A, NTE - Jinx... What can I say about her except that not only is she a poke MONSTER, she can easily turn pokes into all-ins, especially past 6. Janna's kit basically fixes what Jinx lacks: ESCAPE. Like seriously, Jinx only has her dinky snare to get away from mean bruisers and assassins, so unless she's obscenely fed or the assassins are just bad, she won't survive. Play really aggressive but ward hard because a jungler can really screw up your day. Late game, she's going to be very powerful with AOE 1000 damage rocket crits and that cork of hers so make sure you're ready to fend off a 3 - 5 man dive...
Poke, P/A, LGM, NTE - Since Kog'Maw has no escapes, Janna can really help him farm safely. This would probably be a defensive Janna lane, where the lane is passive until the jungler comes in for a gank. If engaged upon, just disengage because Kog'Maw isn't that strong until late game, similar to Vayne.
Poke, All-in, P/A - Lucian is very strong in early and mid game with extremely high burst damage spells and autos, especially if he's not stupid and actually uses the Lightslinger passive. He's gonna want to trade a lot early because of his kill potential, but honestly I wouldn't really pick Janna with Lucian. They're kind of on two different brainwaves.
Poke, All-in, M6, MFE->LGM, NTE - MF can be good with Janna because of her high poke damage with Double Up. Also, MF's passive works well with Janna's passive and helps her escape ganks with Janna's tornadoes. Janna can also make plays to keep the enemy inside MF's ulti. Janna helps MF bully their enemies in lane, and if MF can get fed, she can easily shred a team with Janna pealing for her.
Poke, P/A, NTE - Sivir and Janna don't really synergize very well together because Sivir and Janna suffer the same problems that Graves/Janna does; Sivir is just better with some hard CC to ensure a double proc on Sivir's Q. Although Janna's shield DOES buff Sivir's damage, especially once she hit's 6, this is not an optimal lane.
Poke, P/A, M6, NTE - A somewhat uncommon ADC, Teemo and Janna can work well together if they cooperate and communicate well. Teemo's emphasis on early harass with auto attacks and Janna's shield synergizes well, while he can pretty much escape anything other than hard chain-cc with Move Quick and Janna's tornadoes. Also, their engage is really scary because if the enemy bot lane engages first, Teemo can blind the enemy ADC, and once the blind is up, Janna can chain the disables with her tornado and Zephyr. Once they both hit 6, Janna can make plays, forcing them into Teemo's mushrooms. This lane is really hard to gank for the enemy jungler, but the enemy bot lane can easily shut this down because of how fragile Teemo is early on. Just remember that Teemo has global taunt and you'll be fine.
Poke, All-in, M6, LGM - Oh god, Tristana and Janna. First of all, Trist is probably never going die in this lane because of her Rocket Jump and Janna's tornadoes. Also, even though Trist is a bursty-AD like Graves and Sivir, her higher mobility and less emphasis on bursting, make her a terror with Janna because Janna's disables combined with Tristana's ever-increasing range can out-kite enemy ganks, out dps enemy bot lanes, and later, insta-kill people. When both Trist and Janna hit 6, they can pull off some freaky stuff with their ultimates; 2 knockbacks are REALLY strong together because they can completely lock down a single enemy in their lane and then bully the remaining enemy. They work well with ganks because of this chain-cc.
Poke, P/A, MFE, NTE - Also a rare pick, AD TF can really benefit from having Janna because TF's low range and natural squishiness can be evened out by Janna's shields and tornadoes, though it would probably be better to pick someone like Soraka for higher sustain. Remember that TF is prone to getting harassed hard and that his ultimate will sometimes take him out of the lane. TF and Janna can also chain Gold Cards and tornadoes into some crazy plays with Janna's ulti. AD TF and Janna can do well with ganks because if AD TF gets ahead, he can try to punish enemies for getting into his range.
All-in, P/A, LGM - Twitch and Janna CAN work well together... This lane has a different play style than the other lanes because this can be an offensive Janna lane or a "protect the low-range ADC" lane into a surprise party. This is because Twitch's new stealth mechanic with his Venom Cask benefits greatly from Janna's shield and high utility. Twitch has really high sustained burst damage and high burst with his Expunge spell. Because he's so squishy, sometimes the enemy lane can just turn around and 1-shot him, but Janna denies that. Janna can keep Twitch alive long enough to kill the enemy laners and pull some really scary surprise parties with him. This lane is very powerful with ganks because of Twitch's high damage output.
Poke, All-in, P/A, LGM, NTE - Oh Varus, how Janna loves you. Janna and Varus work very well together because of his Q poke with Janna's shield, and her ability to disable the enemy long enough in skirmishes for him to get a 3-Blight Piercing Arrow or Hail of Arrows off. If Varus uses his Hail of Arrows to proc his 3-Blight stacks, Janna can help him follow up with Zephyr and auto attacks while once they both hit 6, they can chain their ultimates so hard that the enemy bot lane will need a Janna themselves to deny this lane. Varus synergizes perfectly with the passive/aggressive style because he is very similar to a DotA style champ where you poke a lot and then go for an all-in when you can get the kill. Once Varus is 6, this lane becomes stupidly easy to gank, but it's still pretty easy to gank pre-6.
All-in*, P/A, LGM - Janna and Vayne... an interesting lane. They work similarly together like Kog'Maw and Janna, but Vayne and Janna is a better lane because of Vayne's higher mobility and the ability to stun. Although Vayne is still better with Taric or Blitzcrank, Janna can set up some pretty nice Condemns for her to capitalize on. Also, since Vayne's pretty much the squishiest ADC early (other than Kog'Maw), she benefits from Janna's utility and shields. This is an excellent gank lane because of the possible chain-cc. One good tornado can lead to a double kill if Vayne can stun and kill someone. However, this lane can also go the opposite way because if the Vayne gets bullied too hard, Janna can't really do too much for her. In this lane, Vayne can be a little more ballsy than usual because of Janna's safety, but Janna has to be a lot more vigilant than usual because Vayne can be so easily instakilled.
Janna's Friendly Junglers:
Alistar just has disgustingly good ganks for pretty much any lane. He's one of your best friends FOREVER. Also if you're feeling REALLY mean, you can play ping pong with them as Ali knocks them towards you and you ult them back. At 6 this combo makes it pretty easy to blow them into your turret given the right circumstances.
Amumu and Janna can chain their CC like no other; he's your little yordle buddy, especially once he hits 6. His high CC makes it easy to split the support and ADC if needed as well as you can easily reposition yourself to ult.
Jungle Blitz is very rare these days, but he's a good friend because of his high CC and the hook. Blitz and Janna can chain their CC hard and easily ensure a kill for the AD, no matter who it is.
Cho'Gath's ganks are very strong with Janna and an AD like Vayne where you can easily set up chain CC. It's hard for Cho to hit his abilities though, so here it's best for Janna and her ADC to engage the enemy, only for them to find a 2v3.
Jungle Darius is not your friend. He steals your kills with his ultimate QQ. Just kidding; Jungle Darius can be good with a Janna lane, but it really depends on your AD. Darius has no hard CC except his wimpy little pull so if you have an Ashe with Janna, even better.
Jungle Diana can gank a Janna lane pretty hard once she hits 6 because of how hard she hits the low MR laners down bot. It's best if the AD also has some CC here because of how low CC Diana is; her Moonfall just doesn't cut it all the time.
Mundo's ganks are really scary in a Janna lane. Perma slows from cleavers, constant damage from the ADC, and Janna's disables spell some easy kills. If Mundo misses his first cleaver though, the gank will be really hard if you choose to follow through.
Evelynn's power comes from popping up out of nowhere, and she can become a very powerful ganker for a Janna lane when Janna hits 6. If Janna can split the two laners and Eve comes in guns blazing, The poor sap who got split into you is probably dead. However, pre-6, Eve can't gank this lane with huge impact unless the enemy pushes up and doesn't have a pink ward.
Surprise Party Fiddlesticks with that fear forever... He's where you get your namesake, Surprise Party Janna Split. He's a good friend because of his silence and fear. Janna and the ADC can follow up on his engages really hard, and once he hits 6, proceed to collect free kill.
Jungle Fiora has pretty much the same problem as Shyvana and Udyr; she gets kited really hard. However, with Janna and an ADC with CC, her high damage output can really ruin somebodies day... Not not your day, the enemies' days.
Jungle Fizz basically has the same situation that Jungle Fiora has, but once he hits 6, all his problems go away except that he's kind of squishy until he gets some of his items. The shark is really good with Janna's CC.
An uncommon pick these days. GP is rather weak early, and not even Janna can alleviate this. Fortunately for him, with the ADC they might be able to pick up a kill, but it's not probable.
Jungle Fatman! He can gank for a Janna lane decently with his attack speed debuff and slow. Once he hits 6, he has a ranged Janna ulti that does damage, and they can chain their ultis really hard. He can easily secure a kill for the ADC, with or without CC.
Jungle Hecarim, or Horseyman as some people put it, can be really good for a Janna lane. If Hec comes in behind the enemy and pushes them back, Janna can chain her ulti with it and keep them disabled for a really long time. Also, Hec can carry if he gets really fed.
Jarvan IV and Janna can do well in a gank, or just fail really hard. If there isn't a lot of communication, J4 might ulti when you're trying to disengage with your ulti, ensuring not a kill for your ADC, but likely, rage from J4. However, if there is clear communication, they can have really strong ganks with the chain-ccs.
Jungle Jax works best with an ADC that does lots of damage. Jax and Janna can chain their cc while Jax and the ADC shred the enemy hard.
A rare pick, Jungle Karthus' walls of destiny can be chained with Janna's cc pretty hard. Also, it lets Karthus and the ADC use their sustained damage to overpower the enemy bot lane with the armor/MR shred from Karthus' wall. Also, with a Karthus in general, you can call for him to use his ultimate and then engage on the enemy bot lane even without a gank. This is because Karthus' ultimate will do a good 250+ at level 6, and this can help secure a kill early.
Kayle does stupid damage early, and works best with Janna and an ADC with CC. Janna can help Kayle abuse her early damage really really hard because of her high utility. It's best if Kayle can hit her slow early in the fight to amplify whatever damage that Janna and the ADC do.
Free Win the Blind Drunk's ganks with a Janna lane are really good. He's your best blind friend because of his absurd damage early and the cripple on Tempest. It makes it hard for the enemy ADC to fight back while your ADC shreds him. Free Win works best with Janna when Janna can make a play so that the enemy is cc'ed when Lee throws out his Q, ensuring the hit.
Jungle Malph works best with a Janna lane after he hits 6. Pre-6 it's very hard for Malph to gank a lane in general because of his low Q range and no gap-closer, but if he can get close to your lane's enemy ADC, he can shut them down with his attack speed debuff and slow, so try to force the enemy into Malph.
Maokai is the reason why Janna is a tree hugger. He can chain his CC with Janna really hard pre-6, making him one of the best junglers to gank her lane. He doesn't do too much damage early, though, and since there's so much CC between the tree and Janna, it's best if the ADC has a lot of damage.
Master Yi is not your friend. You can't really help him gank your lane that hard even with tornadoes, and even once he hits 6, you'll have a hard time making a play for Yi and your ADC.
Spider Naut is similar to Blitz and Amumu because it's really easy to secure a kill for your ADC if all goes well. Janna and Naut's chain cc is just stupid, especially once they hit 6. The ADC has to be asleep for this gank to fail if Naut and Janna play well.
Nocturne is a good ganker for a Janna lane when the ADC can CC the enemy. His fear is good with Janna's tornado and Zephy, but he can be kited if he misses his Q. Try to help Noc not get kited.
Jungle Nunu should be focusing more on counter jungling rather than ganking, but his Ice Ball and ulti synergize well with Janna's kit. He can gank especially well when the ADC is more on the damage side.
Jungle Olaf can work decently with a Janna lane, but if he misses the Undertow, it will be hard to pull off the gank. Just keep them close to Olaf and far enough away from your ADC that they can't turn and instakill him, and you can out damage the enemy hard.
Jungle Mantheon's target stun works well with Janna's chain CC. Once they both hit 6, Janna can make some serious plays with the ganks for the ADC. Also, you can sandwich the enemy bot lane with Mantheon's ulti if you and your ADC are chasing them.
Jungle Rammus is pretty much never seen anymore because he gets outclassed pretty hard. Rammus can roll in and chain his CC with Janna's if Janna makes a good play. If they can chain their cc, the ADC pretty much has a free kill.
Rengar has powerful lane ganks with Janna, especially because she has such good zone control. She can force the enemy bot lane closer to the bush that Rengar is waiting in and then engage on them. Rengar is prone to getting kited though, so try to help him allleviate that.
Jungle Riven is good with Janna if they can chain their CC well and burst down the enemy hard. Jungle Riven has more sustained damage than burst damage, though, and her stun only lasts like almost one second, but once Janna hits 6, she can keep the enemy bot lane in Riven and the ADC's face.
Jungle Sejuani's infinite slows synergizes well with Janna lanes and make it really easy for Janna to make plays splitting the enemy, etc. She works best with Janna when the ADC has more damage because Sejuani's flaw is no damage.
"SHACO OUT OF NOWHERE!" Shaco pretty much works well with any lane that has a hard CC for him to capitalize on; this includes a Janna lane. He can secure a kill for the ADC pretty easily with Janna's disables.
If you're lucky enough to have Shen, send him top; he's better there. But if you do have a jungle Shen, remember not to tornado them until the taunt is up, unless you have to engage with it. Also, ping and call for Shen's ultimate and you can bait the enemy bot lane really hard with a low HP ADC or Janna.
Jungle Shyv has a hard time ganking because she has no gap closer until level 6. Janna can help her not get kited, but Shyv still doesn't work too well with Janna because she also doesn't have any sort of CC.
Jungle Skarner works best with Janna once they both hit 6 because he can grab them and Janna can lock them down, making the poor grabbed enemy and easy kill for the ADC.
Talon can work well when Janna and her ADC have some more CC rather than damage because Talon focuses (almost) exclusively on damage. Remember that Talon is an AD mage so shielding him can buff his burst substantially.
A rare jungler, Jungle Taric works very well with a Janna lane because of the targetted stun. Taric's armor shred and Janna's disables can give the ADC an easy kill.
Jungle Troll can disable the enemy bot lane really hard and force them into Janna's spells. Alternatively, Janna can force the enemy into Trundle and use Trundle's poopy pillar to her advantage. It's best if the ADC has more damage because of Trundle's pillar.
He has a slow and a dash, making it easy for Janna to help the ADC pick up a kill with Trynd. He also scales hard off AD so shielding Trynd can sometimes be a better idea than shielding the ADC.
Jungle Twitch... Basically the same thing as laning with Twitch. She can really help him do all the damages, but on the other hand, if Janna and the ADC don't help Twitch fast enough, the enemy lane can just turn around and instakill the squishy rat.
Udyr gets kited. Hard. Help him not get kited. It's rather simple. We've been over this with all the other junglers who get kited (Fiora, Shyvana, etc.). If he can hit his stun, you can follow up with tornadoes and slows to make for an easy kill for your ADC.
Volibear is pretty much never seen anymore in the jungle, but if you do get a jungle Coca Cola Bear... I mean Volibear, remember that his toss is slightly smaller than a Singed Fling, and that it's his only CC other than his (rather weak) AOE slow. Adjust your tornado aim accordingly and help him not get kited because he gets kited really hard too.
Warwick becomes your best friend when he hits 6 because of Infinite Duress. WW's ulti and Janna's disables can completely shut down a target in lane while your ADC is a'pew pew pew'ing, leading to an easy kill.
Wukong is kind of a weak ganker pre-6 if he isn't played well, but his ganks become stupidly good once he gets his ulti, especially in a Janna lane. If you see Wuk coming in for a gank, try to help him stealth into a Crushing Blow -> Nimbus Strike instead of forcing him to use his gap closer first. It's preferable that your ADC has CC pre-6, but once Wuk is 6 it doesn't even matter anymore.
Win Nhao is in the jungle? Oh god why. His damage is REALLY good early game, but all he really has in terms of CC pre-6 is a slow from his Audacious Charge. Try to help him stay on his target if he doesn't have boots yet because he can get kited if he doesn't have boots or phage (and his gap closer is down). It should be pretty easy for the ADC to pick up a kill with a Win Nhao gank.
Jungle Zed is a rather weak ganker until level 6 because of how hard he gets kited, but like Udyr and Shyvana, Janna can help him not get kited as hard. Once he hits 6 he becomes a monster, though, and his burst is comparable to Talon's, if not higher. Your shield would not go to waste on him!