Yeah, what about it?
I do agree that chansey should move up a bit, but not to A. It has good synergy with another staple on ORAS stall - mega sableye. I see A- as fit for it, since it's still wrecked in the face by a bunch of new megas like gallade and lopunny, but it does wall lots of other megas, like special altaria, diancie, camerupt, pidgeot etc.
A- is fine for it.
However, I disagree with the fact that slowbro should move up to A+. In ORAS, there are better counters to zard-x like altaria, and mega medicham isn't that common anymore. Mega gallade can set up all over it, as long as scald doesn't burn, and if it has knock off, slowbro is dead. Also, it doesn't make a lot of sense when a mon that has an arguably better mega, it ranked higher than it's mega. So because of that, I think that mega slowbro should move up to A+. It has scary physical bulk, and shell armor isn't even that bad because it's literally crocune v2.0, except it can't be critted. It also walls mega gallade, and lots of other physical megas. It just about outclasses slowbro in every way except for regenerator and leftovers, and it doesn't even care about regenerator that much because most of the time it will be spamming calm mind, so it won't even want to switch out a lot.
I hope that made sense n_n