The Jaguar 2 had a custom RISC processor.
And so did the "1" - you weren't supposed to use the 68000 really, it was more of a bugfix/developer smoothing incident.
The riscs had a good few bugs in them AFAIK and so the general computing model and compiler generated code was hurting/failing. The 68000 meant developers could get code working much faster than getting to know a new architecture and having to work out whether the game bugs were hw or sw. The riscs thus became accellerators.
Wasn't the 2 supposed to be more or less a cleaned up Jag with the 68000 dumped and more 3D oomph? Someone will correct me any moment now.