This one isn't for having a great strategy, but rather to make your opponent throw their game ds/3ds/switch at the wall.
Catch a Shuckle (make sure it has the ability sturdy)
Get it to level 100 (you see where I'm going)
3.Teach it iron defense (you know, to raise that defense), rollout (when you use iron defense 3 times, you'll see.),Protect (ahh, nothing like hitting protect WITH A Z-MOVE), and when all else fails, rest to heal back all hp.
4.After this, put a focus sash on Shuckle for MAXIMUM rage.
5.Then battle. You should see a message that pops up that says "The match was ended". After that you know you succeeded.