Veynuz
I do have various themes for all of me by the way. like in the sense of character/combat themes like in an rpg or whatever

for Veynuz, the character theme is Beautiful Lie from New Danganronpa V3. a busy track, but a calm one. suitable for relaxing as well as interacting with others. meshes well with veynuz's relaxed situation.

Now, veynuz IS a noncombatant.... but, were it to engage in any sort of combat, Be Careful, Everyone! from In Stars And Time fits quite well. It's most certainly a combat theme, but it's reasonably lighthearted despite that. This is no fight to death, certainly.

Railkou
For Railkou, a good character theme is CITRUS! by Lianhua. More intense than veynuz's, with a number of additional computery noises to bring it together. Though I'd be remiss to not mention Spark Engine from 20XX, which served in this spot for years.

And as far as combat themes go, doBuusagi music's remix of Pandemonic Planet from Touhou 15 is the goto. Unlike veynuz, Railkou is absolutely a combatant; in fact, it'd work well as a TH15 Phantasm boss!
DuoRogue
DuoRogue's character theme is the Il Siracusano Lobby Theme from Arknights. Deliberately casual; this isn't the resting state, but actively curating a specific mood and atmosphere, with power beneath the surface.

DuoRogue's sheer ability means that there's hardly one specific battle theme that would function for it; but you can sure do a lot worse than.... honestly, like half the songs from Mad Rat Dead. Mad Heart and Mad Rat, Die stand out, but it would be reasonable to apply Emmental Catalepsy, or Mimolette, or Kind of Hope....

Undrasol
Undrasol, meanwhile, uses Lucid Dream (also known as: the book 4 map theme) from Fire Emblem Heroes. Several themes from House of Pandemonium Remastered work as well; particularly, the Forest Theme and Regulus City.

And for a battle theme, M-Poly's arrange of yukari's fighting game themes, Dismantler, is the song of choice. A refined and respectable power, but not an insurmountable one.
