Genesect has one weakness, Fire. Now he still has that fire weakness, only it's 2X, and not 4X. Awesome.
Genesect @ Life Orb
EVs: 4 HP / 252 SAtk / 252 Spd
Timid Nature (+Spd, -Atk)
- Ice Beam
- Hidden Power [Water]
- Bug Buzz
Thunder is there for awesome coverage, gets rain boost! Ice Beam completes bolt-beam coverage.
HP Water gets rain boost, and covers his only weakness, while Bug Buzz is STAB.
This is probably my most reccomended set.
Genesect @ Choice Band
EVs: 4 HP / 252 Atk / 252 Spd
Jolly Nature (+Spd, -SAtk)
- Shadow Claw
- Metal Claw
Uh.. I really couldn't give you a good reason to use this set.
U-Turn scouts, + Choice band damage is deadly.
Everything else is crappy coverage, but Metal Claw may boost your attack.
Overall, just go Special, and you're a top dog, total beast.
Rating for the rain - 9/10