I'm going to be honest here, i still consider Mega Gallade as quite the unexplored Mega.Debatably as in most of them. Stop nitpicking.
Btw I forgot to put this in the update but we're also considering Skarmory for A- > A. Long story short, spikes, defensive utility, phasing, etc. Had this stuff before but it's more or less fantastic in meta right now. I'll put in later shortly in the actual post.
I'm not a fan of Mega Gallade at all, I think it's a pretty overrated mega but ben thought that M-Cham should be a rank lower than on the premise that SD / Drain Punch M-Gallade is a very legitimate option even more so on many teams because it maintains longevity and still has the capabilities of wall-breaking after a set up without dropping Mega Gallades defense putting it in range of an easy revenge kill. Shadow Sneak, as many like to call shit, can pick off the majority of offensive teams so granted people are gonna downplay these assets but there is a reason why M-Cham is lower at this point.
I'll comment on more stuff later in terms of raises and drops. I could go ahead and explain why M-Houndoom shouldn't rise, again, but I think it's a wasted effort at this point. Also Keldeo going to A+ like trc is a thing with me as well. There isn't anything new that maintains its S rank position at this point and more or less trc's post covered it up.
You see, Gallade in itself used to be a very versatile pokemon, with a plethora of sets & ways to be played, completely changing its playstyle, like Choiced, Sub 3 Attack, SD, Sub BU. All different sets who can fit into different teams.When Mega Gallade arrived, we didn't exploit that much of said versatility & ran one set that seems to be the set: SD 3 Attacks, but many things remains unexploited, like Gallade's half decent bulk, and the 2 others sets i mentionned right before ( Sub BU & Sub 3 Attacks ) could fit into a good amount of teams as well.
Anyway, long story here, based solely on the classic SD Gallade, i'd put Gallade & Medicham on the same rank myself, but it honestly has a lot more options than 1 Setup move + a bunch of good coverage, and it is the main thing that would set Gallade appart from Medicham. ( I mean, these options are possible due to Gallade's better bulk or speed or because Medicham lacks it )
Also, while i'm still on the subject of fighting megas, i'd like to see some discussion about Heracross Mega, as i don't feel that he's exactly a B+ Rank either, even considering his incredible matchups vs some kind of teams. But you see, with the " decline " of stall, Mega-Cross lost a bit of its viability to me, then again, it's been a while since i've ran Mega Cross at all so i'll just end here & ask you all to thing about:
Heracross ( Mega ) -> B?
Gallade ( Mega ) -> B