What about pokemon and digimon transformations? And if the knowledge from another world's species works can't any imagined species work? What about ben 10 aliens, marvel mutants, inhumans?
it's good that you didn't share everything especially about then being fictional characters. too many make that mistake (mostly in SB). what about fairy tail dragons or Pokemons or ben Ben 10 animal form aliens?
He could combine attribute from various specie s into is base form and also create is own dimension, universe or realm with the specie he has from fiction to real world and other but ideas for the future