I found a good suggestion for any mmorpg in reddit. The suggestion is-
What if we can hunt legendaries (more than bst 600) but can't catch them? They will be spawned by server every six or twelve our a day. They will have huge life/hp (like 100000000) and will not be catchable (even after using master balls) and killable at one encounter (because of their huge hp). Raid boss will end if it dies (if someone is battling but others have already killed it, the players will be able to battle but it will not be counted). It will be spawned randomly in the map (if it is spawned in hoenn,