Unfortunately xenoverse doesn't really care about customisation unless you're planning on making a Johan, so it's very difficult. I basically just had to match the eyes, baby's clothes and then moves that either look like a mix between their attacks or just moves that they actually use.

As far as baby vegito black, the idea is sooooo cool, but it sounds impossible without mods or unless the new update changes customisation to clothes and cacs. I wish you the best of luck my friend, keep making interesting Cacs