Based on the roster listed at WWE.com (and who actually wrestle):

Alex Riley - Although he's technically wrestling in NXT. So he probably won't appear in a match at WrestleMania. They're probably just lazy and haven't moved his profile yet.

Bo Dallas - Currently working in NXT again? Unsure. He's been teaming with Tyler Breeze. Although that might only be at live shows? Again, unsure.

The Bunny - Was Justin Gabriel and hasn't been on TV for over thirty days. Most likely because Justin left WWE. So I doubt we're seeing The Bunny anymore.

Chris Jericho - Still listed at WWE.com in their active roster, but probably not wrestling at WrestleMania 31.

Christian - See above.

Dwayne "The Rock" Johnson - See above.

Hunico - So Hunico is Sin Cara. Well, the WWE version that doesn't botch as much. And WWE Sin Cara is in a match. I find it amusing that Hunico still has a separate profile though.

Sheamus - Probably returning in either the Ladder Match or Battle Royal though.

Xavier Woods - Will probably just be ringside during the Tag Team Fatal Fourway.

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As for the Divas:

Alicia Fox
Cameron
Emma
Eva Marie
Layla
Naomi - Will probably just be ringside during the Tag Team Fatal Fourway.
Natalya - See above.
Rosa Mendes
Summer Rae
Tamina Snuka - Torn ACL.

Sheamus is really the only one that I'd actually want to see there.

Well, I'd like to see Layla, but that has nothing to do with wrestling.

Rosa might be at ringside for Fandango when he's in the battle royal