TWW didn't have cuccos either.
Ok .... someone spoiled me something that i need to be verified by the people here ...
Is it true that THERE ARE NO CUCCOS ?
No bird to slash and something insane to happen ????
It works for the same amount of time as it normally would. If you wear the Potion Medal when you drink it and then quickly talk to him it will last as long as it would if you were wearing the Potion Medal (even though Medals technically are not supposed to work in Boss Rush).
I believe it works for 3 complete fights.