Psychic is a funny type to use in Monotype and i think it deserves more attention.
The team has great mons,Silvally-Psychic isn't for sure the best option,Musharna and Claydol aren't use that much but we will se now.
You also miss some op Psychic Mons like Slowbro,Jirachi or Tapu Lele.
-Slowking-Galar
His set is kinda bad to be honest,i use him a lot and i prefer him with Assault Vest.
In my opinion you should just use the Smogon set cause it's a really good one,also if it is for OU.
Just go for Future Sight,Sludge Bomb,Flamethrower and Scald.
-Cresselia
To be honest i didn't used Cresselia beside Trick Room so i'm not sure about her,i also never see her outside Trick Room so i wold just replace
her with Slowbro.Slowbro is a really strong mon that can take a lot of hits and give you momentum with Teleport.
-Silvally-Psychic
Silvally normally should not getting used in Mono Teams in my opinion.
I would go for Tapu Lele which is really crazy atm,also fairy type covers the Dark Weakness of your team.
-Latias
Pretty Nice set but you should make that a Little More Offensive By using spAtk EVs or you can try to use it like this,but use Recover and not Roost
and go for Psychic and Dazzing gleam.
I would Just use Latios With 4 Moves,cause he has a large movepool that can help you a lot,energy ball,thunderbolt,aura sphere,mystical fire ecc.
I would choose for Psychic,Thunderbolt,Aura Sphere and Mystical Fire.
-Claydol
I think that you have a lot of choose for a Rapid Spinner.
It can work,i wouldn't use Substitute,maybe use Dazzing Gleam instead for a little cheap on Dark Types.
I think that another option might be Mr.Mime-Galar with eviolite,but i never used him so i don't know.
I think EVs will be from Smogon so they should be good like that.
-Musharna
Musharna isn't that good to be honest and also that EVs Spread is like kinda weird.
I would just go for Jirachi that is really good in that tier,you can go for the normal set with choice scarf iron head to have a physical sweeper.
It would then looke like this.
