Can you unlock the boss rumblers?

[itsmaxmileaf]

Love this game (and I don't even particularly like soccer!), fully believe arcade sports are making a comeback, and this is the tip of the spear. That said:

Without too many spoilers, fen and the gang seem really cool, but aren't on the main rumbler select screen. Are they unlockable? I understand they might trivialize the main campaign, but having an option once you finish would be awesome (or even beforehand...aint nothing wrong with a broken run once you've earned it!).

Thanks in advance!