I don't know how you're doing for character count, but some non-canon/hypothetical fighters could be fun; thinking along the lines of Super Dragon Ball Heroes (Kanba, Golden/Metal Golden Cooper, Kamioren, Lagss, Hearts/Godslayer Hearts), YouTube 'what if's' from MasakoX (various super Saiyans of Raditz, Nappa, Bronze Cell, etc) Salad Saiyan (various super Saiyans for Turles, God of Destruction candidate Piccolo, etc), maSTAR (Akumo, and Ardos mainly), etc could be interesting; as well as some of the more popular DBAF fighters such as Xicor, and Rycon. The field could be spread to make some of the fan favourites relevant to gameplay (where fighters such as Nappa, Raditz, King Vegeta, Turles, and other such fighters are utterly worthless and goes very early on in other similar games).