Celebi has a colorful movepool, offensively, defensively, and support. You can have strong sweeper, a tough tank, wonderful wall, or a supporting fairy of annoyingness.
Sceptile has a great offensive movepool, on the special side he has Leaf-storm, Energy-ball, Giga-drain, Hidden-power, Focus-blast, and Dragon-pulse, and on the Physical side he has Swords-dance(for boosting), Earthquake, Rock-slide, Leaf-blade, Acrobatics, X-scissor, Crunch, Hone-claws(boosting), Pursuit, and Thunder-punch.
Torterra has a great movepool, he can be used as a wall, a tank, or even a Rock-polish sweeper! Tons of support options and stall moves he is a great Pokemon with tons of uses.