In Sonic Battle stars don't really determine the skills' rarity (it's kinda all over the place really) with the only indication of rarity being specific rare skills - color palettes, idle stances, support skills, "???", Combo skills and Ultimate skills, all of which will not be included in this mod as far as I know.
In any case, given how here they will determine rarity, I wonder how many people will be stuck with only Chaos's jump action, Shadow's ground shot and air shot and Knuckles's/E-102's ground power and E-102's air power.