Anubis' theme song would be Hero by Skillet: https://www.youtube.com/watch?v=5bIDvc_6XGc

Cryo's would be Gasoline by Halsey https://www.youtube.com/watch?v=zRHNi3QfFlE

Darkstalker's (In this au) would be Revived by Derivakat (*caugh* i don't care that it's a dsmp song *cough*) https://www.youtube.com/watch?v=lCpszkhqV-o

Lastly, Cryostalker (Cryo and Darkstlaker sharing control of Cyro's body) would be Alive from Jekyll and Hyde https://www.youtube.com/watch?v=B8TeLugPKqA

There are more characters but they aren't as important (Yet) so they don't get theme songs freaking LOSERS