Rarity is now pure frequency
A Bobo's rarity now comes only from how many live Bobos share each of its traits, with no manual adjustments. A Mutation Bobo is scored on its mutation alone. It used to score a bear type as well, which pushed the more common mutations up the board.
One rule sits on top: the 51 hand-animated Bobos get a 1.1x boost, so an animated Bobo outranks its still twin.