How to decide which battle classes for Imaginators?

So I have the capability to reset my creation crystals, I dont have one of each element yet but I want to only have the minimum I need for completion sakes.

The thing is, I dont really know which battle classes I should choose for which elements, does it even matter? Do they all play identically no matter the element/class combo?

ive never actually played with an imaginator before because I was waiting to be able to reset them so any info/advice you can give is greatly appreciated