No one here has control over the OP, perhaps Quarky, cant remember.. but it's just an oversight 32X should be on that list..
Sadly no missing Saturn, Dreamcast or N64 Core from the list.
The Atari Jaguar Core runs awfully on WiiU.. believe me I've tried lol unless you mean the new standalone Atari Jaguar Emulator?
BigPEmu? That's still closed source iirc, but it is amazing from what I've seen. It's possible it will eventually go open source according to the dev and if that happens I imagine it will quickly become a RA Core THEN we may see it on WiiU
N-Gage? I'm not familiar with a N-Gage Core on Retroarch.