If a Ditto were to try to transform into a fusioned human, what would happen? Would they transform into the human/pokemon hybrid, just the human half, just the pokemon half, would it just plain fail somehow, what would happen?

eta: Also what if said Ditto tries to turn into a fusionmon just in general?

Also, assuming that the local scientists would make an excess of Fusion Balls because they can't really know exactly how many fusion mons there are, if a character happens to have an extra one by the end of the plot, may they keep it? As a trophy/to give somebody to study five years down the line/etc?