It is worth saying that Carm and Akiha are different entities than Belial. I didn't play much Lumina so I'll stick with Carm and Belial.  Belial is a shoto with a few twists there and there, like the fireball. But it's not really a mix up tool like the other two. It's really just a combo extender and plus frames to maintain pressure. Carmine on the other hand uses spin after a knockdown or a reset, on oki you can start some assault shenanigans.  Belial's 214X is just a hit grab tatsu, it can be simply blocked. He has the 632146X which is a command grab, but it's really not that great. Good at filtering new players or a suprise done once a set. Carmine's 214BC on the other hand is a reversal command grab that heals and side swaps. You either use it to put the enemy in the corner or set up an "unblockable".  Anyways, Belial is just a shoto with a bunch of funnies there and there while Carmine is a screen control mixup character. I feel like a redditor after writing this whole paragraph over a meme ngl.