For now, we're probably fine with the Ranks and I don't like the idea of+/- Ranks. If anything we should split C into two ranks and change D and E into E and F. I also think it'd be best to leave the list without Speedups/Lollis for now. Lollis especially since there is only one Mega they'd have a decent effect on and isn't enough to get it up a rank. Charizard Y isn't A Rank material even with 105 AP.
I'm kinda torn on Mega Rayquaza, it has been not performing well for me at all and yet it was far more effective than Gengar during Diancie's Escalation with the Boss Battles. B feels too low for it and A is kinda high so I dunno. I guess A for now.
Anyhow some other possible rank changes: Medicham and Absol for B Rank? I believe Medicham was discussed a bit in the other topic. But basically it is a Fighting Mega who can boost itself to evolve in a similar speed to Lucario and can combo sometimes (although not very often). If some combos do happen, it easily outdamages Lucario. Its clear is also more of a defensive pattern keeping the middle clear helps keep combos possible.
Absol for B Rank is more or less because Ghosts and Dark struggle heavily with disruptions on the board and Absol is one of the few that can clear them. The others being Sharpedo who can't really get the disruptions below it and Sableye whom is well.... Sableye. Apart from Absol, our best Ghost/Darks for fighting disruptions are Trevenant with Swap+ and Bisharp with Rock Break+. There are no Barrier Bash+ nor Block Smash+ Pokemon. There aren't even high powered Barrier Bash and Block Smash Pokemon to use.
Garchomp to A? If Mega Rayquaza stays in A, does Garchomp belong in there too? If not, Garchomp is just on the border. Great type coverage, Mega effect and power. It has some competition, but it often outperforms even Mega Rayquaza in my experience.
Blastoise to D? Disappointing Mega effect, disappointing power and disappointing coverage. It's just so disappointing even with the Raise Max Levels available for it. I mean coverage alone it has to fight with Glalie and Garchomp off the top of my head, whom are far superior Megas in just about every way. Has some little use in Timed and that's about it.
Charizard X to E Rank? How did this even end up in D? I see more use with the Normal Megas in Timed than with this Mega.
Diancie to D? Despite original impressions, it has some very limited use on Finneon and a few other stages with heavy amounts of Barriers (such as Mega Glalie.) You'll still likely need to Mega Start it however.
Blaziken & Swampert to D? I know not happening, but each thread can use this suggestion. Still despise these Megas on Turn Based. Some use in Timed but that's it.
Grass Safari: Sunkern/Petilil/Gogoat
Timezone: Central U.S Timezone
Breeding for 6IV Female Eevees while searching for Shinies. Or 6IV Females really supposed to be as rare as an actual Shiny??