Ferrothorn
Seems like a good set. However, I'd recommend Spikes over Stealth Rock, since 1. you can potentially have other Stealth Rockers in defensive Tyranitar if you do pick it. Given Ferrothorn's great bulk and positive matchup against a good percentage of the Pokemon in National Dex, it likely will be able to set the Spikes up more than once, which is key in supporting your squad, especially Mega Lopunny.
Tyranitar
Ok so for one, Specs Tapu Fini does not exist, and nunber two, Tyranitar can by no means switch into Specs Lele's Moonblast. I think since you're using Excadrill, you're better off using something like a Leftovers or Smooth Rock support set, which has the ability to run Stealth Rock too. Of course, Choice Band works just fine.
Tyranitar @ Leftovers / Smooth Rock
Ability: Sand Stream
EVs: 252 HP / 252 Def / 4 SpD or 252 HP / 4 Def / 252 SpD
Impish / Careful Nature
- Rock Tomb
- Stealth Rock
- Pursuit
- Thunder Wave
Tyranitar @ Choice Band
Ability: Sand Stream
EVs: 252 Atk / 4 SpD / 252 Spe
Adamant Nature
- Stone Edge
- Crunch
- Pursuit
- Earthquake / Fire Punch
Excadrill
Groundium Z is pretty bad and does nothing to fix Excadrill's problems, like with Tangrowth and Landorus-Therian. I believe that if you're going to use a Z-move, Steelium Z is a much better option, since it can overwhelm them pretty quickly with hazard support and a Swords Dance boost, something that it cannot do at all with Groundium Z Earthquake. You can also run Leftovers if you want to focus on Excadrill's spinning ability, but considering you have Defog Zapdos, I think Steelium Z is the better option.
Victini
I do not understand this at all. Why are you running White Herb if you can just get out of there with U-turn? Choice Scarf or Choice Band are likely much better options.
For Band, it can probably use all those moves, with the option of Trick to cripple physical walls.
Victini @ Choice Scarf
Ability: Victory Star
EVs: 252 HP / 4 Atk / 252 Spe or 252 Atk / 4 SpD / 252 Spe if running Bolt Strike
Jolly Nature
- V-create
- Final Gambit / Bolt Strike
- U-turn
- Trick
Zapdos
Looks good, except I'd recommend using other EVs. This is supposed to be a defensive Zapdos set.
Using the standard 248 HP / 188 Def / 72 Spe and a Bold Nature should do. Your team I can see doesn't like the Gliscor MU, especially if you drop MLop's Ice Punch / Axel for U-turn, so you can use an offensive set.
Zapdos @ Heavy-Duty Boots
Ability: Static
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
- Discharge / Thunderbolt
- Heat Wave
- Hidden Power [Ice]
- Roost
So far I haven't found any use for Smogon's offensive Zapdos EVs on your team, since all of its damaging moves are used on rain and aren't that good outside of rain, except Hurricane but you need Heat Wave for Ferrothorn and IcePower for Grounds so it can't really fit here. I think Leftovers is more valuable on Excadrill if you choose to run the offensive Zapdos set for more hazard control.
Mega Lopunny
All you have to do here is replace High Jump Kick with Close Combat. You don't want to be scouted for a potential U-turn or Fake Out with Protect and instead lose 50% of your HP, or miss the move in general. An Ice move looks nice at first, but remember that not only does MLop take tons of damage hitting Garchomp with Axel (esp if its a defensive Chomp with Rocky Helmet). U-turn I think would be better here as it lets you scout switches and come in and scare the opposer out.