I think I would prefer a second opinion on Mega Ttar.Tyranitar: 155 base Attack STAB Technician priority borders on anti-competitive. Technician would also boost BOTH INDIVIDUAL HITS of Dragon Darts and Gear Grind, giving them like 200 BP, which is bonkers. Here are some calcs for it:
Froslass: Every other weather setter beats Froslass in addition to a bunch of other stuff. Buff its bulk.252+ Atk Technician Tyranitar Gear Grind (2 hits) vs. 252 HP / 252 Def Weezing: 360-424 (107.7 - 126.9%) -- guaranteed OHKO
252+ Atk Technician Tyranitar Gear Grind (2 hits) vs. 252 HP / 252 Def Dunsparce: 580-688 (143.5 - 170.2%) -- guaranteed OHKO
-1 252+ Atk Technician Tyranitar Gear Grind (2 hits) vs. 0 HP / 252 Def Scrafty: 198-234 (53.3 - 63%) -- guaranteed 2HKO
252+ Atk Technician Tyranitar Gear Grind (2 hits) vs. 0 HP / 0 Def Necrozma: 276-326 (82.3 - 97.3%) -- guaranteed 2HKO
252+ Atk Technician Tyranitar Gear Grind (2 hits) vs. 0 HP / 0 Def Togekiss: 306-362 (84.7 - 100.2%) -- approx. 6.3% chance to OHKO
Silvally: The old version would have been cool, fun to play around with if slightly completely broken. This is fine though. It doesn't have any Fairy coverage, which is a fairly critical type right now, so consider giving it one of the two viable Fairy moves.
Froslass’s main niche is to quickly set up Aurora Veil and switch out, similar to Ninetales-Alola. I will buff it’s bulk a little though.
I’m sorry, but I completely don’t understand your concern about Silvally. It literally carried coverage for everything, meaning countering it was completely impossible. Just because a Protean mon has low type coverage doesn’t mean it can’t be threatening (ex. Greninja). Overall I feel it was too broken even for me and tbh, it may need to be nerfed a bit more.