Some suggestions I would give:
Mimikyu: I think you forgot that Curse, when used by a Ghost, cuts its HP in half in return for cursing the opponent. That is actually good, however, as it allows Mimikyu to faint itself when at low HP to safely bring in a stronger sweeper. If you do want Mimikyu to do damage, though, opt for good old SD over Curse, and shift over SpDef EVs to Atk.
Ursaluna: Tera Fire is usually not necessary. SD boosted Fire Punch blows through most things that Fire Punch needs to, and using Fire means you are giving up to more nuclear Tera types, such as Normal, or more defensive types, such as Ghost. I would go for Normal since, after all, there are several Psychics and Fairies on your team to deal with Fighting mons.
Hatterene: Slot Psychic over Calm Mind, Trick Room over Stored Power, and Sash over Lefties. You don't want one Pokemon doing all the TR support, and Hatterene does it especially well due to Healing Wish fainting it instantly and allowing another Pokemon to come in safely. Psychic and Draining Kiss provides it with the decent dual STAB if it wants to do some damage, but in my opinion, it's a premier Trick Room suicide lead, and it should be used like that.
Kingambit: I don't like the Fighting Tera, as I generally prefer Tera Dark, for powerful Dark STAB, or Tera Flying, to provide more defensive leeway. The lack of Sucker Punch (hell, the lack of prio on your team in general), while reasonable given the Trick Room context, is risky, since Trick Room won't be up all the time, and when it's not, Kingambit's screwed. Therefore, I feel like giving Sucker Punch to Gambit over Kowtow Cleave or Iron Head is recommended. Replacing Kowtow means there is no type overlap, but Steel in general is a bad Offensive type. Personally, I would replace Iron Head. Also, Black Glasses on Kingambit for even more powerful Dark STAB.
Enamorous: So what do you do against, say, Corviknight? Although you do have Ursaluna to handle it, it's only one mon that has SE coverage. I personally bring Mystical Fire over Draining Kiss, as I usually don't want the recovery of Draining Kiss. With something as short as Trick Room, you want to squeeze every KO you can possibly get before it runs out. Make sure to have Boots as well, there is zero hazard removal on your team (Hatterene can't do all the hazard blocking) and Enamorous really benefits from it.
Cresselia: First things first, Tera Poison. Poison Cress is so infuriating to get rid of, and with Gambit already dealing with Psychics, Tera Poison Cress can be quite the nusciance. You could also run Trick Room on Cress, but honestly if you are going the triple setter route its best to choose another mon. I personally recommend Glowking, as its Regen ability coupled with Chilly Reception makes it a good setter and pivot in general.
