Let's be real here, Teemo's in a shit spot right now.

Honest to god, the shroom "buff" did not do that, his AP ratios are gutted, and the only somewhat viable build path on him, being the On-Hit Teemo build, got nerfed hard when Guinsoo's was changed, and AP Teemo is just too weak. His Q is pretty much useless as a blind now, it doesn't block Hec E dmg, doesn't block Voli Q dmg, doesn't block Yas's Q (it does say it's pretty much classified as an AA in it's tooltip) It doesn't block GP passive from being applied, and I can name so much more. It's at the point where you max W before Q and just use Q as an auto attack reset to proc Thunderlord's faster. His shrooms last for too little, and are easily countered. And even when hit, the damage is negligible, you have to hit 2-3 just for it to actually be something to worry about, and they're easily countered by the buffs to Red Trinkets. The bouncing shrooms are nice, but the entire change to his kit their ended up being more of a nerd than a buff, as being able to throw the shrooms isn't worth losing half the duration of them. Honestly, I pray Riot can bring Teemo back up from the grave, I mean, they did it to Swain and now he's viable, they did it to Malz and he WAS viable. They know how to make interesting changes to champs that could work, but if they're either too OP or nerfs, and if they're too OP they either get gutted, unless they're Zed, Nidalee, or LeBlanc.