Character UI:
ui/replace/chara/
ui/replace_patch/chara/
chara_0 = Record Portrait
chara_1 = CSS Portrait/Boxing Ring Portrait
chara_2 = Stock Icon
chara_3 = Vs. Portrait/Results Portrait
chara_4 = Battle Portrait
chara_5 = Spirit Portrait (No Alts)
chara_6 = Final Smash Portrait
chara_7 = CSS Icon (No Alts)
chara_10 = Pokémon Trainer Pokémon Masks
chara_12 = Boss Portraits
chara_13 = Alternate Battle Portrait (used for unmasked Joker)

Stage UI:
ui/replace/stage/
ui/replace_patch/stage/
stage_0 = Series Logo
stage_1 = Small Portrait
stage_2 = Normal Portrait
stage_3 = Omega Portrait
stage_4 = Battlefield Portrait

Series Icons:
ui/replace/series/
ui/replace_patch/series/
series_0 = All instances except...
series_1 = Results Screen Transition Series Icon

Spirits UI:
ui/replace/spirits/
ui/replace_patch/spirits/
spirits_0 = Full Spirit Image
spirits_1 = Battle Portrait Mini-Icon
spirits_2 = Full Spirit Image Silhouette
spirits_3 = Master Spirits