I somehow obtained a certain modded version of both Sonic Riders titles and these are the characters I found in them:
Jake (Both)
Cassie (Both)
Tobias (Both)
Marco (Both)
Rachel (Both)
Aximili-Esgarrouth-Isthill (Human morph) (both)
Hahaha this is another one of my lame jokes... but I wish I had the know-how and the tools to actually mod these characters into either game