Ferrothorn @ Leftovers
Trait: Iron Barbs
EVs: 252 Def / 252 HP / 4 Atk
- Thunder Wave
- Leech Seed
- Power Whip
Well, Iron Barbs hurts like...iron..barbs. T-Wave slows the opponent down to make up for Ferrothorn's atrocious speed. Leech Seed is HP recovery and with protect and T-Wave wrecks havoc. Power Whip hurts, a lot. If you're expecting a fire attack switch to Heatran and get the Flash Fire boost.
Ferrothorn takes neutral damage from ground moves and with the bulk takes them quite well. Fighting is now your only problem. as a Defensive poke Ferro can take pretty much every physical fighting move. Mind you this is why we are not limited to two Pokemon in a team.
So my second suggestion if you like Ferro is,
Go with Gyarados, make him a physical attacker. He can take the fighting hits and deal massive damage in return. If your expecting lightning, well Ferrothorn resists.
Gyarados @ In-Game I'm not sure, I'd give him a Water Gem for the set.
Trait: Intimidate (if you can get his dream world ability wonderful)
EVs: 252 Atk / 252 Spd / 4 SDef
- Dragon Dance
- Ice Fang
Waterfall is an HM in-game and is very powerful. If you're feeling lucky you can get a flinch. Water Gem boost on it for massive damage. Earthquake hits lightning types and some others. Ice Fang hits dragons and grass types. DDance is for set-up.
Intimidate works nicely for lowering the attack. Moxie is even better with Water Gem/Waterfall lead.
So between these three you have a mostly perfect defensive core and a brutal physical attacker.