List of which textures are who. Thanks to Aaron for assembling this list! Few minor tweaks by myself (Warchamp7)
~And special thanks to various members for identifying once-unidentifyable textures! (S.)

FitCaptain01 = Viewtiful Joe
Fitcaptain04 = Ronald McFalcon
FitDedede04 = Fat Bandit (Heartless Dedede)
FitDedede06 = King Hohoho
FitDiddy03 = Power Wild
FitDiddy04 = Bouncy Wild
FitFalco04 = Olcadan
FitGanon03 = Manfred Von Karma
FitGanon05 = Lynx
FitGKoopa = Dry Giga Bowser
FitIke02 = Felix (Golden Sun)
FitIke05 = Kingdom Hearts Cloud
FitKoopa05 = Dry Bowser
FitKoopa06 = Violet Bowser
FitLink05 = Fierce Deity Link
FitLucas01 = Jimmy Neutron
FitLucas03 = Phoenix Wright
FitLuigi00 = Mr. L
FitLuigi05 = Iluxig
FitMario03 = Shadow Mario
FitMario05 = Heartless Mario
FitMarth01 = Angelo
FitMarth04 = Wander
FitMetaknight03 = Meta Vadar
FitMetaknight05 = Galacta Knight
FitNess03 = Earth Lover Zim
FitNess05 = Invader Zim
FitPeach00 = Strikers Peach
FitPeach03 = Rosalina
FitPikachu01 = Plusle
FitPikachu02 = Equim
FitPikachu03 = Minun
FitPikmin05 = Jack-O-Limar
FitPit03 = Serge
FitPit05 = Cupid
Pokemon Trainer and Co. 01 = Mario Trainer and Co.
Pokemon Trainer and Co. 04 = Gary Oak and Dark Pokemon
FitPopo02 = Kiddy Climbers
FitPurin00 = Boo
FitPurin01 = Sharingan
FitPurin03 = Byakugon
FitRob04 = Meat Grinder
FitRob05 = Prometheus
FitSamus04 and FitZSSamus04 = Dark Samus and Dark Zero Suit
FitSamus05 and FitZSSamus05 = Phazon Suit and Phazon Zero
Zelda and Sheik 04 = True Midna and Tall Midna
Zelda and Sheik 05 = Rosa (Final Fantasy IV) and Shadow (FFVI)
FitSnake04 = Old Snake
FitSonic01 = Shadow
FitSonic04 = Metal Sonic
FitToonLink05 = Toon Skywalker
FitToonLink06 = Fierce Toon Deity
FitWario02 = Dr. Wario
FitWario07 = Booster
FitWolf03 = Vegeta
FitYoshi04 = Black
FitYoshi05= White

Textures that aren’t working:
FitKoopa00-04
FitPikmin03 = Louie
FitPopo04 = Unknown (wasn’t it the Ice Mages?)