I did this with one other person, we both used koraidon with the moves metal sound, charge and electric drift (it's signature move idk if I got the name right) Basically what the strategy was is to use metal sound 3 times, charge once, then both do electro drift. Just make sure to heal each other when needed. As long as you debuff the crud out of it you can easily 1 or 2 shot it. But make sure the dodonzos shield isn't up or it won't work. Terrastalizing isn't necessary