I always get the to the last wave of the gym, but I always only have one candy left :< Using uh
Top left: Pikachu (Thunder Wave)
Top Right: Oddish (Solar Beam)
Middle: Pikachu (Thunderbolt)
Bottom left: Mankey (focus energy + karate chop)
Bottom left: Rattata (focus energy + hyper fang)
I'd put the oddish in the middle, the two pikachus at the bottom(change to thunderbolt), and mankey/rattata on the top right/left.
Edit: You might want to grind that oddish into a gloom.