>>54052255I imagine, for gen 10 at the very least, that fusion as a gimmick would be extremely limited, if not ever then at first.
Say, only Gen 10 pokemon can fuse initially. Furthermore, knowing GF, ICLA, etc., there would be one design per fusion. No head/body shenanigans, just one A×B fusion, like how there isnt a Grey Reshiram or Grey Zekrom, just B/W Kyurem. There would likely be fewer new mons to allow the team to design and model the fusions, probably comparable to the Natdex portion Kalos is allotted, and even given that, Kalos has only 71 new additions. That alone means there are 71(71+1)÷2, or 2556, fusions under this more restrictive model of fusion, assuming any Gen 10 mon can fuse with any other Gen 10 mon, with only 1 fusion per pair.
If we were to expand this to every Pokemon, including a hypothetical 71 G10 mons, it would be 1081 mons, or 584821 unique fusions.
This doesn't even get into how the stats would be arranged, unless the base stats are simply averaged.
My point is that this would be horribly overwhelming, on several fronts. Some would be cohesive while others wouldn't, and some have opposing concepts entirely. God bless those behind Infinite Fusion, and they have but 1/5 the fusions to deal with iirc.