I agree with ultimate flygon.You need to have a strong Pokemon like GYARADOS that should finish things off in a second. seems good although it seems slow.So a trick room slowbro will be good. is rather okay other than its High SpDef stats.But off all the three I would go with gyarados beacuse of its high stats of 540.
A good moveset will be:
Gyarados (M) @ Lum Berry
Role: Physical Sweeper
EVs: 4 HP / 252 Atk / 252 Spd
Adamant Nature (+Atk, -SAtk)
Lum berry Prevents yourself being Confused and most importantly Burned ( I hate that )
And Moxie boosts are very helpfull, along with an Adamant nature for the hardest freaking hits you can give away.
Dragon Dance to set up with, and then Waterfall for STAB, Earthquake for Coverage, Stone Edge for Other Gyarados's and other coverage.