Eternatus
This is pretty good but I would replace Eternabeam with either Flash Cannon or Shadow Ball or if you decide to remove the Scarf, then you could use recover.
Dracovish
Nothing to change except maybe removing Ice Fang with a Dragon move
Zacian-Crowned
Usually I would say to have Fire Fang for Corviknight but you have 2 Fire type attacks on very heavy attackers so it's fine to not do so.
Darmanitan-Galar
Pretty good so all that could be changed is maybe using Stone Edge instead of Zen Headbutt though you get nothing against fighting types if you do.
Marshadow
I wouldn't replace it with Dragapult because too many weaknesses would overlap on your team. Also the moveset is good but maybe you could use Ice Punch instead of Iron Head since there aren't too many fairy types except Zacian which takes neutral damage anyways. Also if you really wanna be that person, you could use a Focus Sash.
Ditto
The thing with Ditto is, it copies every stat except HP all you need is a full HP investment I think.
I hope I may have helped.