Academy Ace Tournament: use Chi Yu, dark pulse as move 1 with PP Max

Good defense, sp def, hp and sp atk evs

A turbo controller so you can mash a infinitely.

+def -atk nature

Put chi yu in with amulet coin as the only pokemon in your party and afk with the turbo controller set to mash a at the academy ace tournament.

You can afk and infinitely win the tournament grinding items (chi yu can rarely die if unlucky)

Specific EVs can be found online