Not sure if this is posted already but this is from Uutitan. Anyways... Here it is:
Clefable @ Leftovers
Magic Guard
Bold: 252 HP/152 Def/104 SpD
- Follow Me
- Softboiled
- Seismic Toss
- Encore
Drifblim @ Lum Berry
Unburden
Bold: 252 HP/80 SpD/176 Spe
- Stockpile
- Skill Swap
- Baton Pass
- Swagger
Regigigas @ Lum Berry
Slow Start
Adamant: 4 HP/252 Atk/252 Spe
- Psych Up
- Return
- Ice Punch
- Drain Punch
Crobat @ Expert Belt
Inner Focus
Timid: 4 HP/252 SpA/252 Spe
- Roost
- Heat Wave
- HP Elec
- Taunt
Idea is: First, send out Clefable & Drifblim... Use Clefable to absorb attacks with Follow Me, and have Drifblim use Stockpile. Try to get as many stockpiles in before Clefable dies, and heal Clefable if need with Softboiled, only if you think Drifblim is beefy enough with a good number of stockpiles in. Have Drifblim set up Substitute if you get a chance, once the 3 Stockpiles are in, that is. Then, once Clefable dies, switch in Regigigas. Regigigas will now use Psych Up to copy Drifblim's stats up (the +3 Def and +3 SpD), while Drifblim will Skill Swap away its bad Slow Start to get it going.
Currently:
* Drifblim (Substitute, +3 Def, +3 SpD, Slow Start)
* Regigigas (+3 Def, +3 SpD, Unburden)
Next, Drifblim will use Swagger on Regigigas to confuse him. Lum Berry will activate (only do this IF Lum Berry has not yet been used up), activates Unburden, doubles both Regigigas's already monstrous attack and speed. With its beasty base HP, Def and SpD, it's practically invincible with +3 in each defenses, and its Adamant-Max Base 160 Attack after a STAB will kill just about anything. It's Drain Punch is probably enough to OHKO Regirock, and at the same time, heals this beast.
On the other hand, Drifblim, if it hasn't died yet (maybe still has sub if you had an opportunity to set it up earlier), Baton Passes its +3 Def and +3 SpD to Crobat, who can Roost off damage, and giggity-goo everything else with special attacks while Regigigas takes cares of physical attacks (although with that stats, it doesn't really matter)...
If you think one of your opponent has Taunt, Haze, Whirlwind or Roar, which can kill off the plan, use Gigas to take it out, or both if you fear a Sash, before they uses Whirlwind. Crobat is also fast enough, can taunt others before they get to use Taunt... Can also kill threats like Gyarados with HP Electric and Scizor with Heat Wave. The Defense Boosts are great, and allows it to Roost off damages, as I mentioned earlier...