Tips for playing against a Teemo who is ahead (I'm not his lane opponent)
There is only so many times I can activate the Oracles and control wards I can hold. Is there anything besides that and just basically not building your carry role (aka just go tank) if you are a carry? Just don't feed the Teemo?
to push sidelanes (because shrooms won't stop them).
Group mid and slowly advance with the wave. Don't go in the jungle, there is only death.
Force them to deal with you while the tp jungler similarly advances after the mega-minion.
Basically play like normal, but far more methodical.