Help with Bruno and rest of the Elite 4, Mono Dragon.

I have managed to make it through the whole game so far, doing a monotype dragon run but I cannot get past Bruno on the elite 4, Zacian and Iorn valiant are destroying me and I've been at this for days. This is my current team, I need help with team suggestions, changes, strats etc. Willing to swap teams entirely.

Dragapult: Jolly, Choice Band Mega Altaria: Adament Archeludon: Quiet, Leftovers Baxcalibur: Adament, Loaded dice Hydraigon: Modest, Choice Specs Garchomp: Adament, Life Orb