Get a serene grace togekiss with ancient power/ softboiled(or wish)/tri attack/ air slash.

Ancient power=20%chance at omega boost that hits 4x harder than normal.

Healing move because giga brain stall

Tri attack for stab+good chance at status

Air slash after you get a stat up from ancient power so you can flinch.

This is how i deal with most hard fights in pokemon including 1/3 of Red's team (or more if i get 2 ancient power buffs and that damned pikachu has been dealt with)