All Morphs of a given type deal the same damage, have the same speed, same hit properties, etc. Only the secret characters (Poseman, Scarf, etc) are different. Most of them are straight upgrades (elemental imbued) save Gun and Bomb's. You should still switch around your leader to level everyone up for Skills and bonus Morphs.
I think certain (non-secret) Wonderful Ones have special properties, but I don't know which. The only one I know is that Wonder Beer can go normal speed with a Unite Morph out, rather than being slowed down.
Not tricks, Michael, illusions. A trick is something a whore does for money.