After a bit of thought, Ultimate Marvel vs. Capcom 3 (and 2, honestly) would also be interesting to look at. 2 is essentially a booked game, I don't think anybody feels like new stuff is going to be discovered there, but it was actively played for years and years, so examining changing tier lists would be pretty interesting. 3 is still played and the metagame has gone through some pretty significant shifts (from phoenix teams to morridoom to zero may cry), but I can basically guarantee that it's not going to be patched any time soon because of the way rights to the characters are tangled up, so any metagame shifts that happen are entirely due to the players discovering new tech. And there's definitely still a lot of new tech to be discovered in MvC3.