Jesus can Mega Manectric drop to A- already? That thing is so ass in the current metagame when comparing it to other Megas such as Zard-Y, Latias, Mega Venu, Gard, and Medicham, who can all pull their weight in pretty much any battle. While the decrease in Hippo is kind of helping it, the ever so common Sand offense is still at an all time high, and pretty much every team is packing some kind of offensive Ground-type such as Exca or Scarf Lando-T. The meta is also conforming to bulkier and fatter builds, which Mega Mane struggles against because it fails to break through anything that can avoid the 2HKO from it pretty easily. Mega Latias balance/bulky offense is really hyped right now, and once that hype goes down Mega Mane could rise in viability again, but with it being one of the most popular megas atm, it's practically a liability against most teams. In fact, Mega Mane has a terrible matchup against a large variety of builds you see popping up, especially the ones with CB T-tar on it or Hoopa-U bulky offense. I would say Mega Mane is honestly not THAT much better than Raikou at this point, because while Mega Mane has better coverage and can check a wider variety of threats thanks to its Speed, Raikou at least as the ability to threaten bulkier builds thanks to its CM set, which can set up on the likes of Mega Latias and Amoonguss. It also doesn't take up a mega slot, so you're able to use an Electric-type with another mega such as the Zards or Medicham.
Thundy by far the best Electric-type in the tier that hasn't really dropped too much in viability since the meta shift, and ironically I wouldn't really use Mega Manectric without Thundy as a partner to it so it can lure in bulky Grounds with Grass Knot as well as wearing down other common Electric-type switch-ins such as Clefable and T-tar. Otherwise it's just so easy to mindlessly switch into and take advantage of, especially with how much Mega Mane hates hazards.
I also agree with Mega Alt dropping to B+. Unlike Mega Mane, there really aren't any particular sort of builds that Mega Alt actually excels at pressuring. Practically every playstyle has something for it; Offense has Weavile, Mega Meta, Excadrill, and Diancie, bulkier builds have Mega Venu, Jirachi, Mega Scizor, Amoonguss, and Skarm. Even after setting up plenty of Pokemon can still take a hit from it because it lacks the raw power of most set up sweepers, and its either lacking coverage to hit many of the aftermentioned threats which causes it to be hard walled by practically any decently built fat team, or lacking recovery which makes it very easy to revenge against faster, more offensive teams. Mega Hera even looks more appealing than Alt at this point, because at least Hera can completely tear apart bulkier builds and is practically impossible to switch into versus offense. Mega Alt is neither hard to switch into, or hard to wall. The special set is the only set I'd even consider using these days because at least it can smack Steels and Tangrowth around pretty hard without having to set up, and offense doesn't really have a good switch-in to it outside of an offensive Steel.
Lastly T-tar needs to be A+. Even if Hoopa-U leaves, it's still going to be a very dominating force that is practically the face of the metagame right now with all the Sand offense running around as well as Pursuit being so good. Mega Latias being very dominant is helping it out a lot too, which is probably why CB is becoming one of its better sets, as most of its common switch-ins expecting a Scarf Stone Edge will find themselves 2HKOed.
