My team:
Kamex
Blastoise @ Blastoisinite
Modest, 252 SPA/252 SPE/4 HP
31/X/31/31/31/31
Water Spout
Dragon Pulse
Aura Sphere
Protect
Not much to say. STAB Water Spout off of 135 base SA murders everything. Protect is very crucial and using it well is key. Protecting first turn while MChar destroys a Grass or Electric is nice. Also lets MChar fire off EQ without hurting your Water Spout's power. This thing is bulky even uninvested- he took unstabbed Thunders, Energy Balls, etc without a hitch.
Drim
Excadrill @ Life Orb, Mold Breaker
Jolly, 252 ATK /252 SPE/ 4 HP
31/31/31/X/31/31
Metal Claw
Earthquake
X-Scissor
Rock Slide
Rarely ever had to use him. I think he absorbed a Tbolt for Blastoise a couple of times but that was his entire purpose. I initially selected him to cover a few weird things I'd had trouble with in previous runs- Metal Claw for those super S-Def fairies (Iron Head unavailable, I know), EQ for steels, X-Scissor for Lati@s. Really he could've been any ground type, but I felt he had better synergy all in all over something like Garchomp. In retrospect Mold Breaker was a bad idea as it would nullify my own Gengar's Levitate, but I was originally worried about Sturdy last pokemon. I never was in a situation where he had to kill Gengar with EQ.
Partner Team
Fury
Charizard @ Charizardite X
Adamant, 252 ATK/252 SPE/4 HP
31/31/31/31/31/31
Flare Blitz
Dragon Claw
Earthquake
Dragon Dance
This guy. I know Charizard gets a lot of hate, but man did he work well with MBlastoise. MCharizard is a near-perfect Linebacker for MBlasty, taking out the nasty Grass and Electric 'mons that would not mind Water Spout. Dragon Claw dented bulky waters hard, too, putting them in KO range of Water Spout. I never had a problem with Water Absorbers- I only encountered two- Vaporeon once and a Storm Drain Cradily once. Dragon Dance rarely got used, in retrospect I would've made that Protect (damn speedy Darmanitans with never-miss Stone Edges). Pretty simple- Grass type? Flare Blitz. Electric/Sturdy? EQ while Mblasty protects. Dragon Claw to death anything else. The only thing that routinely gave him trouble was Darmanitan, who would die to Water Spout same-turn. I rarely attempted to sweep with MChar- his existence is solely to allow Blastoise to kill everything.
Virgil
Gengar @ Focus Sash
Modest, 252 SATK/252 SPE/4 HP
31/X/31/31/31/31
Shadow Ball
Sludge Bomb
Dazzling Gleam
Thunderbolt
Gengar saw very little use as well- generally only came in to help Blastoise clean if Charizard took an unlucky Stone Edge to the heart. Using Sash, I prefer Modest since he's generally guaranteed at least one attack. Large sampling of coverage to kill things that might pose trouble for Blastoise- SBomb for Grass, DGleam for Dragon, TBolt for waters. He did his job well when called upon.
Things that hurt:
Not much can take a STAB Tough Claws Flame Blitz/Dragon Claw followed by a STAB 150 BP Water Spout. Darmanitans outsped and 1HKO Charizard with Stone Edge on three occasions. Jolteon outspeeds but can't KO and dies to DClaw or EQ. Surprisingly, I didn't see a lot of electric types- Electivire popped up most but rarely attempted to use Electric Attacks. ChestoRest Lanturn was not threatening but obnoxious with a Stockpile or two- it would generally be the last pokemon and I'd have to keep trying to get a crit. The one Storm Drain Cradily I encountered was terrifying- the only battle I had which got me down to a single pokemon. Excadrill killed it with Metal Claw, but it was a very close call. Teams that lead with an Electric and a Grass were very rare but the most difficult and required some fancy Protect use.