well garchomp is a very serious pokemon if trained in speed, if it has jolly and 31 ivs in speed, its nothing to laugh at..
the best chomp would be
Garchomp @ life orb
EV distribution: 252 speed, 252 attack, 6 HP
Move-set: Swords Dance, Substitute, Dragon Claw, Earthquake/Fire Fang
this is one of the most ideal OU pokemon to have on your team, it can have up to a max of 333 speed, out running most other pokemon built for attack, while it lacks in attack, you can give it a life orb to up the amount of attack it was missing.