I got bored and made what I would love to see as costumes for Dante from Devil May Cry were he to make it into Super Smash Bros. Ultimate. I may do Jill Valentine later on.
HUGE Pic, so I put in a Spoiler Tag.
Now, there are some things I would add that I couldn't due to a lack of skill, such as the particular patterns on the outside and inside of the Vergil's coat for the Vergil reference alt and a denim texture on the pants for Diesel reference alt.
I figured that Dante's coats being different shades of red in each game would be enough of a difference to work as alts similar to how Sonic and Cloud work.
Spirit Battles
Vergil (Dante, Vergil Alt), has Killing Edge, level is Reset Bomb Forest post Bomb, music is The Duel (DMC5)
Lady (Bayonetta, White Alt), has Super Scope, level is Arena Ferox, Omega, music is Devils Never Cry (DMC3)
Trish (ZS Samus, Black Alt), has Death's Scythe, level is Mallet Island, music is Lock and Load (DMC)
Nero (Dante, Nero Alt), level is Coliseum, Omega, music is Shall Never Surrender (DMC4)
Lucia (Lucina, Cherche Alt), level is Dracula's Castle, music is Away (DMC2)
Nico (Bayonetta, Yellow Alt), Random Kapp'n ATs, level is Four Side, music is Devil Trigger (DMC5)
V (Dante, DmC Alt), Random Assist Trophies, level is Luigi's Mansion, music is Devil Trigger (DMC5)
Nelo Angelo (Ike, Black Alt), Random Final Smash, level is Mallet Island, music is Ultra Violet (DMC)
Mundus (Ganondorf, White Hair Alt), Random Andross AT, level is Dracula's Castle, music is Ultra Violet (DMC)