@K112 You said the magic words to a Soulcalibur enthusiast lol! You have Cassandra Alexandra,, Isabella Valentine for - Soulcalibur 6 outfits. There are other designs from Soulcalibur 2, 3, and 4 (Ivy has one in SC5 also) that are all great, but you've picked the best to start.

Most female characters:
Sophitia Alexandra - SC4 and SC6 are especially good designs (Cassandra's big sister in Greek flowing outfits)

Elysium - Soulcalibur 5 (basically a Sophitia clone with a translucent outfit)

Taki - Soulcalibur through Soulcalibur 6 (ninja type in various skintight bodysuits)

Amy - SC3, SC4, SC6 (gothic lolita dress)

Tira - SC3 (best version imo) through SC6 (torn chaotic outfits reflecting her dual personalities)

Seong Mi-na - SC through SC6 (athletic bra + loincloth design)

Setsuka - SC3 through SC6 (geisha themed outfits)

Talim - SC2, SC3, SC4, SC6 (tribal priestess design)

Xianghua - SC through SC4 + SC6 (elegant Chinese design)

Hilde - SC4 and SC5 (knight warrior type)

Leixia - SC5 (Xianghua's daughter with a similar design)

Natsu - SC5 (similar design to Taki but blonde with more accessories)

Pyrrha Alexandra - SC5 (Sophitia's daughter, similar design to her, but not quite as skimpy)

Viola - SC5 (pale gothic magician vibe)

Major male characters: (in case you wanted to go all out)

Astaroth - SC through SC6 (giant axe wielding barbarian)

Mitsurugi - SC through SC6 (samurai warrior type)

Siegfried - SC through SC6 (blonde knight type)

Cervantes - SC through SC6 (undead pirate type)

Nightmare - SC through SC6 (monstrous corrupted knight vibe)

Maxi - SC, SC3 through SC6 (nunchaku bruce lee vibe)

Yoshimitsu - SC through SC6 (masked warrior vibe)

Aeon Calcos / Lizardman - SC, SC3 through SC5

Zasalamel - SC3, SC4, SC6 (time lord reaper vibe)

Yun-seong - SC2, SC3, SC4 (athletic open shirt warrior type)