Alright, guess I'll give my two cents on some of these:
Aromatisse: Aromatisse is still a solid Pokemon, but the offensive nature of the current metagame strains Aromatisse quite a bit. As she doesn't have Regenerator like Alomomola, it is very difficult to keep Aromatisse and her teammates healthy at the same time when the opponent is able to apply offensive pressure. And what can you do better than anything else in an offensive metagame? Apply offensive pressure. This means that Aromatisse is generally forced to choose between keeping herself healthy or keeping her teammates healthy. She's got the same great defensive typing, Aromatherapy + Wish in one mon, and a decent enough offensive presence to keep most setup sweepers at bay, but I feel the meta is a bit too offensive for Aromatisse to fulfill her duties enough to be worthy of A+ status. I think she's fine in
A rank.
Moltres: This one is really controversial.
Arikado raises some really good points, but there's a couple of key factors that everyone has missed up to this point imo. An S rank Pokemon is supposed to be very influential in the current metagame and very easy to support. So, is Moltres very influential in the current megatame? Of course it is. Maybe not quite as bad as it started to get toward the end of XY, but you've still got to have an answer or two to it. This is partially the reason why I run Scarf Meloetta on most of my HO teams as it gives me a one-time switch-in that can generally beat Moltres so long as Rocks are up. I actually have SpDef Golbat on one of my balance teams as a surprise Moltres check, but the point is, you need to have a response or two for Moltres if you hope to win a lot of RU games. Is Moltres easy to support? Yup, it still is. The Scarf set has kind of become the "norm" so to speak with all the fast new Megas and all it really needs is a good wallbreaker (Dragalge, Pangoro, Exploud, Meloetta. Take your pick) and hazard control (Shiftry, Gligar, Skuntank, Hitmonlee, etc.) As you can plainly see, this kind of support is really easy to provide for almost any team, even semistall. For the Life Orb set (which is still dangerous) just get a fast mon / Scarfer over the wallbreaker (so Mega Sceptile, Meloetta, Mega Lopunny) Moltres may not be quite as powerful as it was in XY, but it's still a pretty influential threat that's still very easy to support. For that reason, I feel it should stay in
S rank.
Mega Camerupt: I won't speak on Mega Abomasnow as I don't have experience using it in ORAS yet, but Mega Camerupt definitely should stay in
A rank. I've been using it on a balance / semi-stall team recently as an offensive Rocks user, and it's been very surprising. One thing you really want to do though is run enough Speed EVs to outspeed base 30s after Mega Evolving (84 EVs) This lets you do all sorts of cool shit, like outspeed Amoonguss (no Spore for you!) Cofagrigus, and Slowking (only matters if it's weakened, but still cool af if it is weakened) after Mega Evolution. However, the fun doesn't stop there. Base 40 Speed before Mega Evolution. So what does 84 Speed EVs do for that? Oh, idk, just let you outspeed Doublade, Rhyperior, Druddigon, and Registeel before Mega Evolving. This let's you just wait on Mega Evolving until you're in safely against one of these threats. Then, you just Mega Evolve on them, outspeed them, and crush them with Earth Power or Fire Blast while getting the immediate Sheer Force boost. Mega Camerupt is definitely more at home on a Trick Room team, but by running 84 Speed EVs on it, Mega Camerupt can be surprisingly effective without Trick Room support. That said, it does love to have paralysis and Wish support though, but considering the fact that Alomomola and Cresselia cover its weaknesses very nicely (and are two of the fattest mons in the tier) this isn't as much of a burden as you'd think.
Mega Pidgeot: Yes please. Ok, so I'm probably going to be a bit biased on this one as Mega Pidgeot is my favorite new Mega, but that's only because it's so amazing. It literally doesn't need coverage outside of Hurricane and Heat Wave, which lets it have two free slots to work with. I personally prefer U-turn and Roost as this allows Mega Pidgeot to not only wear down its checks and counters, but also keep itself healthy throughout the battle. Granted, you may not get many opportunities to Roost against offensive teams, but it helps Mega Pidgeot perform better against fatter teams that are likely to have more resilient answers to it. Heck, if you don't want Roost, Tailwind is a great option in that last slot to give Mega Pidgeot and its team a quick burst of Speed to finish out the game with. One thing I don't like on it though is Defog. I think Defog is about the worst move you can have on it. Why? Because it's weak to Rocks, has no Leftovers recovery, and doesn't have Eviolite to bolster its defenses to make up for this. Heck, I feel even Toxic is a better option on it since that actually helps to wear down shit like Cresselia, Rhyperior, Gastrodon, and Slowking. You know, stuff that can actually take multiple Hurricanes to the face? Anyway, Mega Pidgeot is great on Spikes offense / VoltTurn because of its speedy nature, powerful Hurricanes, and tendency to scout with U-turn. Great Pokemon and definitely one I feel is
A+ worthy.