Teach your riolu Force Palm. Granbull’s main weak point is the underside of its jaw. Strike upwards from there, and you’ll throw off its balance entirely.
Good luck!
You do realize that violence is not a good answer, right?—LH
Ah, so you agree that violence is an answer when it comes to neglectful trainers! Excellent! —Bill
I … you’re not going to edit this, are you? —LH
Sigh. —LH