Check: Tank Araquanid.
Araquanid @ Waterium Z
Ability: Water Bubble
EVs: 248 HP / 232 Def / 28 SpD
Relaxed Nature
- Liquidation
- Scald
- Leech Life
- Toxic / Power Split
My favourite Fire blanket is back for another round of destruction - he resists Mega Camerupt's STABs and HP Ice, he isn't 2HKO'd by Rock Slide without Stealth Rock and severe hax (needing damage rolls, Speed ties and flinches to all go in Megarupt's favour), and he only has to fart in Megarupt's general direction to destroy it. Just watch out for Electric Terrain Nature Power variants, as it OHKOs, should Megarupt predict the switch or win the Speed tie.
0- Atk Sheer Force Camerupt-Mega Rock Slide vs. 248 HP / 232+ Def Araquanid: 114-136 (33.6 - 40.1%) -- guaranteed 3HKO (28.1% chance to 2HKO after Stealth Rock)
0 Atk Water Bubble Araquanid Liquidation vs. 128 HP / 0 Def Camerupt-Mega: 552-656 (176.3 - 209.5%) -- guaranteed OHKO
0 SpA Water Bubble Araquanid Scald vs. 128 HP / 0 SpD Camerupt-Mega: 392-464 (125.2 - 148.2%) -- guaranteed OHKO
Needless to say, he has an even easier time against slower spreads, since there's no Speed tie and thus no risk of flinches.