And this is not something exclusive from MMO metas. On Smogon's Gen 7 PU or ZU, i don't recall right now, Mesprit was a top mon. But all that taked to mesprit rise, was a player with plenty of time, to not say other things, spam it from day 1 to 31 on the highest tier. And the meta shifted a lot, Skuntank on that meta became irrelevant overnight. The problem is the same can be done there, just need like you said, 2 players with a full week avaliable, someone alone with a full month free, or you can call like 10 teammates to assist and move a lot of key mons up simultaneously.