Many of the ones I like are already mentioned -Earthquake, Power Whip, Flash Cannon, Dragon Pulse.
Has anyone seen Tauros using Giga Impact? It's really amusing... rather than ramming the opponent with its horns like we'd expect, it's body rotates 90 degrees and it flies at the opponent with hooves.
(Actually I just checked; if you use it, it flies with its back,but I think when the CPU did it in the battle facility, it was facing the opposite way.)