His Passive can be really obnoxious to deal with, especially when he is hiding in a brush and moving in and out while pelting his laner with his Q and E.
He is the bane of ADC mains as his Q quite literally makes them miss their auto-attacks. This can reduce the effectiveness of the carry for a while, which gives his team some time to engage/disengage freely.
The Ultimate R can act as a substitution for vision, as well as deal a lot of damage when kept in the right spots. This is especially useful when it comes to avoiding ganks.
Very squishy and layered crowd control can get rid of him immediately. He is vulnerable when his Q is down, and can be engaged upon if his W movement speed is reduced.
His Ultimate R can easily be gotten rid of by the enemy by purchasing Control Wards. Enemy Junglers with leaps and dashes can also bypass these mushrooms by taking odd routes.
He falls off quite drastically during the late game and can only resort to split pushing. This puts his team in a disadvantageous state and causes a lot of tension to build up within the team.
0 - 15 min
Your goal in the early game is to play safe, pick up gold and XP and avoid dying to the enemy laner. You are rather weak in the early game and need time to come online.
Once you have quite a few levels under your belt, you should look for short favourable trades. As you’re not strong in the early game, you may wish to wait for the enemy to waste an ability before playing aggressive.
Keep the minion wave closer to your side of the map in the early game. This will ensure safety and reduce your chances of dying in lane.
15 - 25 min
Split push during the mid-game and try to secure side objectives. Avoid grouping if possible.
Use your strong duelling potential in the mid-game to fight and duel anyone who tries to stop you from split pushing.
Although you’re a really strong split pusher in the mid-game, be prepared to group with your team and fight 5v5. You should usually start grouping when there are no nearby objectives to take.
Peel for your carries in late game team fights to increase the chances of your team winning the fight. If they die at the beginning, you will not be able to win the fight alone.
Stick with your team in the late game. Do not split up or walk away from them otherwise the enemy may try to pick you off or initiate a 4v5 fight when you’re away from your team.
Focus the nearest enemy champion to your carries and work as a team to take down the enemy one by one. If you focus the backline alone, you may be an easy target for the enemy and may die quickly. By focusing on the nearest champion, you will survive for longer and keep your carries alive.
Level six is the 'power spike' for Teemo. It will let him be extraordinarily obnoxious and sneaky now, especially as the game progresses.
The first item component will increase his overall damage in the game. This will help him in duels and will allow him to use his spells frequently as well.
Multiple items in the first ability will increase the damage and reduce the cooldown of the said ability. It can allow Teemo to do a lot of burst damage.
He can roam around the map and place his Ultimate R mushrooms in heavy traffic areas. It will allow him to detect enemies as well as get kills on unsuspecting low health targets.
His first ability will be maxed out at level 9. This will let him deal hefty amounts of burst damage and will let him kill his enemies quickly.
He isn't outstanding in team fights, so he should either resort to securing picks and blowing people up with his abilities or just split pushing till the enemy responds to him.
Level sixteen will further reduce the cooldown of his Ultimate R and increase the damage of his mushrooms. Enemies will have a hard time traversing choke points now.
He will have a lot of ability Haste now, which means he can drop a lot more mushrooms around the map. The enemies will have to invest heavily in vision to keep themselves safe.
He will complete his build during this phase of the game, which will allow him to one-shot squishy targets. His Q blind should come in handy during this phase of the game as well.