Teemo is a very OP Champ, especially if he has an AP Build and it makes him tanky.

Proes
Poison increases basic attack damage
Blinding Dart makes all basic attacks of its target not work for around 5 seconds
Move Quick increases his movement speed by alot
You can spam Teemo's Ult so muc that u can set up traps that can half kill people
Teemo's Passive can make himself invisible to the enemy team via staying still for 2 seconds

Cons
Teemo is Squishy unless you build him tanky.

I chose this build because it is the standard AP build used in most types of lvl. 30 players.

You should get your blinding dart, toxic shot and your noxious trap as soon as possible in that order.

I got thoughs runes because Teemo is a very good hybrid champion.

I built Teemo as tanky as possible with still dealing massive damage and having some lifesteal.