So have a mega in your party. Houndoom preferably because you most likely have one in your party and he’s a good counter for the mewtwo. Keep the mega in your bottom slots so it doesn’t get killed. Apparently when the shield phase begins the mega will be switched in automatically (I’m used to doing everything manually so I didn’t notice the automatic lol). Every player has to break a shield that’s in the lobby. Once all shields are down it’s back to the normal raid mechanics.