Manectric - Fine standard.
Metagross - Go one way or the other w/this guy. Physical sweeper is best cause his Atk. >>> Sp. Atk.
Meteor Mash<>Shadow Ball<>Earthquake<>Agility
That's the set I like. Boost the speed, the hammer away!
Crobat - This one is up to opinion. For a Toxi-annoyer I don't like him any more. He is decent, but Dusclops, I think does a better job. I'm raising my Shiny Crobat w/this M/S:
Crobat (Hasty) @Choice Band [EV's: 252 Atk./Spd., 6 HP]
Sludge Bomb<>Aerial Ace<>Shadow Ball<>Hidden Power (Fighting)
I lucked out on the HP~Fighting really. His nature sux, but hey, he's shiny so who really gives a rip!
Walrein - You could do that, but I'm thinking a creative set would be more fun here.
Walrein (don't matter) @Leftovers [EV's: 252 Def./Sp. Def., 6 HP]
Rest<>Sleep Talk<>Sheer Cold<>Roar
Now I know this calls for max hax, but hey man, sh!t happens doesn't it?! This guy would be a good pseudohazer cause of his Defenses and Roar, + he'd be perfect for tryin to freeze 00ber @$$es off! He could Rest, the Sleep Talk, and possibly OHKO them or shuffle the fields a little bit. Sleep Talkin Sheer Cold doesn't take away from Sheer Cold's PP. I like this guy a lot, and I'm plannin on raising one myself.
Camerupt - Yep, sort of standard. Maybe Overheat > Eruption since he's a better physical sweeper, but hey man, whatever floats your boat!
For your last slot I kind of feel bad about takin your Water special sweeper away from you, so I'm gonna suggest a poke that could really help out your team, + it's UU.
Golduck (Modest) @Anything [EV's: 252 Sp.Atk./Spd., 6 HP]
Calm Mind<>Surf<>Ice Beam<>Psychic
You have to breed for Psychic, but hey you can hatch till you get the right Nature then too! He adds that Psychic advantage I took from your Metagross, plus CM+Any of his attacks is awesome!
This is a solid team and you don't have to take my suggestions, after all, they're suggestions...