Teemo cannot stop or even escape a majority of their damage, they can also bypass shrooms via blinking spells which is a risky proposition, your best bet is to out harass them in the very early levels before they utilize their mobility spells to burst you.
All highly resilient bruisers that are very eager to crush your pretty face, early on due to how much armor you have, it shouldn't be too much of an issue to survive encounters in close quarters, however later on in the game they can shrug off your damage and reach you with ease if your not careful. Stay highly mobile and utilize mushrooms and move quick to kite and juke your way to victory.
The longest ranged auto attackers in the game, your task of blinding them is nigh impossible in several team fight locations, this is another reason why Teemo shouldn't really be placed within bot lane, as other TRUE AD carries can outclass his harassment and burst capabilities, Teemo's strengths expand as he gets further in levels and attains more map control, and within bot lane its just hindered, crippling my most beloved yordles capabilities.
All of these heroes have semi global ultimates that can bypass several of your shrooms (and even reveal them!) which can catch you off-guard in several occassions, your best bet is to have shrooms located deep within enemy territory to see them sneaking up on you, just keep a close eye on their locations and you can usually survive :) the shroom locations I listed with the previous section allow you to gain a sneak peak at which direction these fellows will be closing in on you from, allowing you to respond accordingly. Dont be afraid to just sit in camoflague leeching exp in a safe position if you are afraid they are nearby.
You CANNOT stop their damage you can bait and dodge a majority of their spells but if they catch you in a team fight you are in a heap of trouble, in the laning phase you should be able to harass quite successfully in the early levels, however once they hit level 6 you are going to struggle to survive due to how low Teemo's base health and magic resist actually is. Its best to avoid fighting these characters in a 1v1 situation. Also this is why Teemo being located in mid is a rather risky move, his bane is hardcore AP carries and in every match the enemies AP carry will be steamrolling mid just avoid picking Teemo if your team already has a solo top.
Top Lane Beasts
All are common in the top lane, and all are a hit and miss when it comes to winning the lane, all have more sustainability than you, and all can synergize with a jungle ganker better. Your best bet is to play it safe and harass in moderation to prevent being ganked in a 1v2 situation, once it hits levels 6 it also becomes an entirely different matchup and you may find yourself losing the lane, it might be time to call for a gank or a switch depending on how well the enemy is doing.
Both long ultimate spell ranges, that can easily focus you regardless of your positioning in a team fight, I DESPISE Xerath with a passion, and Malphite ... there are no words to describe the pain, but all of them can easily focus fire you regardless of your positioning and it forces you to use flash in a majority of cases, the best way to counter them is by utilizing camoflague (if the enemy doesnt have detection) or wait until they have blown their ultimates on more resiliant candidates. Just try to get a clutch flash or activate move quick as you see them charging up to survive.
Pets, annoying little things that explode your shrooms at the most innoppurtune times, there is no real way to prevent them from charging directly at you, as Voidlings and Ghouls have awful AI. Also these three will cause you problems within the lane, ask for assistance from your beloved jungler.
Blinds? Say hi to 6 spells:
Although spell enhanced attacks will not apply when blinded, these three characters can still throw out some decent damage regardless of the blind, basically you wont be saved with low health if they have mana, also they have a tendancy of being painful to lane against as they jump around the place cutting you into ribbons if you dont stay mobile.
Now these heroes are relatively new,they can lunge tremendous distances with ease, and occasionally means that establishing your shroom perimiter can be interrupted, and in most cases you will be torn to shreds early on. They also are a pain to fight from what I gathered, Rengar is one tough kitty to kill and he can keep leaping at you, try to fight out in the open in a bundle of shrooms.
Vi hurts like hell, but shes nothing too serious for Teemo to handle, just beware when she can FALCON PUNCH you to oblivion as it cant be stopped unless you kill her during the animation.
Zac is new, but I really dont have troubles against him, just a simple ward or couple of shrooms, and he wont catch you unaware, in close quarters just keep dancing and prepare for his ult, hes fairly slow moving while in it, so you have a chance to move quick and escape before being tentacle fondled.
Recently, I've been running into GP's and unfortunately the emo version of kayle, which are both hard to put the final nail into the coffin, as they both have ways of just overcoming your harass throughout the laning phase, they also have the capability to throw out the burst regardless of blind, the slows they both pull out can ensure your demise if your pushing your lane too carelessly, aatrox atm is perma banned so not too much worries there.