A simple idea for a teemo rework would be to do this;
Passive- Poison Darts (same as his current 'e'), Slows targets affected by Noxious trap (stacks onto Noxious trap slow)
Q- Same (buff base damage)
W-Same, except breaks all movement impairments
E- Noxious trap, (current tito ult, except projectile speed and arm time is faster, base damage lowered, ap scaling increased, missing hp damage, lower duration, and when cast in melee range (200) Teemo automatically detonates his mushroom (lower aoe).
R-Ambush, After a short delay Teemo becomes invisible for a several seconds (breaks stealth when Teemo attacks an enemy, instead of when moving out of a bush), during Ambush Teemo gains flat ms, and when breaking stealth gains bonus attack speed.
Ambush should have a fairly short cool down.
Teemo should also receive a huge VU that doesn't make him look like a moving hat, try to make him look cool like Omega Squad Teemo, maybe have an option (taunt or something) where you can where the goggles.