So apparently it's neutral to everything there. Plus it only has one weakness and it's immune to ground. What a bonus. Anyway it's bulky if used right (I assume you know how to make a bulky Rotom-W) As I said above, it's neutral to everything. It learns Will-O-Wisp (Ta-da, defensive side of it's bulkiness solved) , Thunder Wave, Toxic, and Confuse Ray. Pretty sure that's it. Oh, and it's OU. Pain Split is for healing, but it's not the most reliable. And then there's Rest...
Rotom-Wash @ Leftovers
EVs: 56 SDef / 252 HP / 200 Def
- Will-O-Wisp/Confuse Ray
- Rest/Pain Split
- Hydro Pump
Not the best, but it resists Bug and Dark, while being neutral to Fighting and Flying. It learns Toxic, surprising. It can get Roost for healing. Also, if you Baton Pass a sub to it then yeah. Bulky Physical Attacker. It's OU. (duh)
Scizor @ Leftovers
EVs: 252 Def / 248 HP / 8 Atk
- Bullet Punch
Baton Passing a Sub works even better, IMO.
Pretty bulky. It learns Toxic, so yeah. Also Toxic Spikes but that's different. The resists Fighting and Bug, and it neutral to Flying and Dark. It can learn Rest, though Protect + rain Dish + Black Sludge heals it significantly. It's OU.
Tentacruel @ Black Sludge
Trait: Rain Dish
EVs: 244 Def / 248 HP / 16 SDef
- Substitute/Rapid Spin
Many different bulky sets for Tenta. This is Toxic Stall