This is a chart I found in the forums showing what type of troops a certain devil uses. I did not check it's accuracy but thought it would help.
Type Name
Merman
Wavewalker = swords man
I use heavy cavalry, sword dancers, and horse archers
Tidecaller =bowman
I use long bowman , light cavalry, heavy cavalry
Seastrider = pikeman
I use long bowmans, swordancers
Leviathan = Sword dancers
I use heavy cavalry and horse archer
Harpy
Wingless = swords man
Skyclaw = bowman
Wind Hunter = Pikeman
Skywalker = Swordancers
Demons Slave = swordsman
Spellsword = Sheildman ??
Arcane Channeller = bowman
Slave Master = pike man