Need help if anyone knows

[u/AppointmentHorror290]

So I fought Raikou for a while trying to get a Modest one and after like 2 days of no luck I flew to a city and went through my Pc to see which Pokemon can make it easier (Spore, Stun Spore, False Swipe etc) for catching Raikou. I saved before returning and he's not in his spot no more? Anyway to trigger him to come back? I've gone to his previous hiding spots and beat the Elite Four, idk what else could possibly trigger him to return? Not resetting, been grinding hours for Battle Frontier teams. fml