Genesect isn't going to switch into Garchomp before it knows what kind of set Chomp is running. CB EQ is a OHKO. Fire Fang kills. Fire Blast kills. No Genesect user in their right mind will be hard switching into Chomp.As much as I love spamming Protect, I have to admit shrang's right. Garchomp has so many more good moves at its disposal - why scout around Genesect when you can roast it on the switch with Fire Blast? Heck, you could even run Sandstorm to fuck with weather teams. Dual Chop hits Dragonite on the switch too.
Feel free to slash in Dragon Tail and Fire Blast, two other good moves that I neglected to mention. The last moveslot is really up to whatever move suits the team best. And don't hate on Protect, Genesect never sees it coming. The smart ones U-Turn expecting a switch, the dumb ones Ice Beam expecting you to be as bad as they are. Either way, they're in for a beating. Protect is good on almost anything, I don't see why Chomp should be any exception.