Help with team change up

So I have beaten the e4 and gail. My team is
Primal Giratina
Delta Gardevoir (choice specs)
Delta Bisharp (Mega)
Hydreigon (Mega)
Delta Haxorus
Armored Ttar

My team is pretty weak to fighting, and I want to continue with post game, so I should change things up. I have always wanted a delta volcarona, but I don’t know what to get rid of (I really want mega hydreigon).