Ok there NEEDS to be a Choice Band set. Quite simply: it's amazing. Theorymon ran some calcs one night and found out stuff like it 2HKOs Reshiram with Gyro Ball and can 2HKO Timid Lugia. It's so slow with a Brave nature and 0 Speed IVs its pretty much always 150 BP. Power Whip / Gyro Ball / filler / filler; Power whip and Gyro Ball are really all you need. Possible fillers are Explosion, Payback, Leech Seed, Level Ground or whatever. It also still has amazing bulk with 252 HP / 252 Atk. Under the rain hardly anything can OHKO it, and Kyogre also has pretty nice synergy with it to boot. No one really expects it either, and it almost always rips gaping holes in the enemies team.
[SET]
name: Choice Band
move 1: Power Whip
move 2: Gyro Ball
move 3: Leech Seed / Spikes
move 4: Explosion / Level Ground / Payback
item: Choice Band
nature: Brave
evs: 252 HP / 252 Atk / 4 Def
ivs: 0 Spe
move 3 and 4 slashes don't really matter to be honest, and the EV spread is subject to change sorta...
But, yeah, this is extremely good. Try it if you don't believe me, it hits like a fucking truck (all credit to Theorymon for this set too!)