depends on what song of course, but for the most part he uses minor keys such as natural minor harmonic minor, phrygian, harmonic minor with the occasional consecutive major 6 and 7.

that one where the dolls sings by herself, the first phrase for the verse is in phrygian with a major 7 at the end. the very end it switches to harmonic minor. or you could just think of as harmonic minor with a flat 2 blue note. making christmas is in harmonic minor. the one in christmas land with jack is in major. the boogie man song is abundantly pentatonic with some minor notes here and there. i haven't seen corpse bride so thats all I can think of at the moment.
Artist: Mad Orca
Album: Plan of Attack
Available on: iTunes, Google Play, Bandcamp, Amazon mp3, Tidal, Spotify