Welcome to PokéCommunity! Register now and join one of the best fan communities on the 'net to talk Pokémon and more! We are not affiliated with The Pokémon Company or Nintendo.
Honestly I would lure Kyruem there to try to stop them from fighting. If that does not work or it only gets worse, i would use my pokemon to try to catch the trio. Ether way i wouldn`t stand there and watch and/or leave.
After you defeat the E4 you can get shiny stones at the pokeatholon(bad spelling).
On-topic: I train all my pokemon to lv 45, stocked up on potions and revives, and made even though it took 4 tries...
My WTF moment was when catching mewtwo.
Ok then so mewtwo was in red. I thew a timer ball....
It missed and then mewtwo used stuggle!!! He died...
And the thing is mewtwo also had known power/guard swap, psycho cut, and amnesia. That was more than four moves!