The Lord of Vermilion series is known for having crossovers. Persona 4, BlazBlue, and King of Fighters characters were in Lord of Vermilion Re: 2. Lord of Vermilion III will arrive in arcades on August 22 with a mishmash of Square Enix villains.
Deathjester and Isabella are from the Japan-only sequel to Secret of Mana. Saruin and Death come from Romancing SaGa. The arcade game even has notable Final Fantasy characters like the smelly Malboro, deadly Tonberry, and superboss Omega.
Secret of Mana 2
Crimson Lotus Wizard