What interactable Pokemon like Volcarona and Kyurem don't obey the rebettle E-4 reappearance rule?

Question

I'm nervous I won't catch my DreamYard Latios, I already KOed it, XD

Answer 1

All legendary Pokemons that can be interacted with can be found again after rebattleing the elite 4
So dont worry you can catch him in other chance
Source: experience and marriland( youtuber)

Answer 2

if you saved then turn ds of and try agen or beat the elite 4 if you did not save.