*spits out moveset data robotic-style*
Gyarados @ Leftovers
Adamant
Ev's: 252 Atk / 252 Spe / 4 Hp (72 HP / 252 Atk / 184 Spe if you to go advanced, assuming you've got 31 Iv's in speed.)
-Ice fang
-Dragon Dance
-Earthquake
-Waterfall
Sweeping Gyara. Dragon dance if you have time, and proceed through their team.
Swampert @ leftovers
Timid (Bold/relaxed is better)
Ev's: 252 Def / 252 Hp / 4 SpA (240 HP / 216 Def / 52 SpA )
-Surf
-Ice Beam
-Roar/Earthquake (If you can get relaxed nature)
-Stealth rock
Defensive sponge. Stealth rock as soon as you can.
Blastoise @ Leftovers (surprise

)
Lax (Bold is MUCH better)
Ev's: 252 Hp / 252 Def / 4 SpA
-Ice Beam
-surf
-Protect
-Toxic
Tankish, toxic, protect, attack repeat.