Well, I'll try and answer this.
Toxapex
Good set (of course it's good. It's mine. Jk lol) nothing to change there
Dragapult
Good moves, but I would change the evs and nature a bit. Use Hasty Nature so you can do more damage with u turn. Also, swap those 4 sp def evs for a better 4 Atk evs. It's not much of a difference, but every stat counts. On the other hand, as Y was saying in the comments, you may keep all your set, but add 0 attack ivs to take minimum foul play damage.
Excadrill
Again, good set, nothing to change there.
Volcarona
Strong set, but one problem is the item. It's life orb/specs, and with volcaronas typing, you need heavy duty boots. While the extra power is nice, being at 51% hp with more power is not. You may or may not want it, but Roost on volcarona keeps it in for longer too, but gets walled by toxapex, so you may want to keep psychic.
Zeraora
Put those 4 extra evs into sp def, as an even nuber of hp can lead to less survival on spikes/stealth rock. (As an extra, try not to make the hp evs even unless you want to belly drum into sitrus berry)Blaze kick is probably better than fire punch, even with the worse accuracy. But, what I would actually recccomend there is a play rough. It covers fighting, which would kill Excadrill, and you already have fire blast and fiery dance for fire type moves, and it doesn't cover much for zeraora anyway.
Other teammate
I would recommend Mew I know you wanted some hazards and mew has toxic spikes, spikes, stealth rock, and recover.
Mew @ Leftovers
Ability: Synchronize
EVs: 252 HP / 8 Atk / 124 Def / 124 SpD
Jolly Nature
- Toxic Spikes
- Stealth Rock
- U-turn
- Roost
For good setup. No spikes because it takes 3 turns to fully setup and could be swept away in one Defog. Also, it doubles the time taken to setup. Roost for recovery, and u turn to switch after. For a bit more offensive mew but still some setup use this
Mew @ Leftovers
Ability: Synchronize
EVs: 80 Atk / 88 Def / 88 SpD / 252 Spe
Jolly Nature
- Psychic Fangs
- Stealth Rock
- Close Combat
- Roost
Hope I helped!
