Gandhara's spirits and mediums.Edit
Ozam uses the Two Kings from the Butsu Zone series as his spirits, and his mediums are two vajras. Samy and Mamy use Ashura, and as for their medium, I think it might actually be Mamy herself. The Japanese wiki gives a comparison to the series Kamen Rider Kiva, but I can't tell what the connection specifically is.
Sei-Kyow (whatever his name is) uses the spirit Marishi-Ten, using a mirror as a medium. Aeon Lee uses the spirit Catura (Shatora is another way to write it) through the medium of his necktie.