I did relearn subversion. I know about Mario and not so much about Rabbids. I believe I can explain why Mario + Rabbids was
not a true subversion.
According to TVTropes website [ref 1] a trope subversion requires the audience to believe there is a trope about to happen. This implies a situation is set up that easily allows a trope to happen. This setup never happens because the costumes in Mario always come from powerups.
There are no powerups in the levels (not including upgrades out of levels), no costumes were expected, and thus no subversion occurs. In light of this I must refer to Rabbids wearing Mario and Princess costumes among other things a trope reversal [ref 2], and an incomplete subversion of the costume trope. So this can also be seen as not a real subversion.
If the Rabbids were to use strange powerups from out of ?cubes in a future game it would be a subversion because we expect power ups to be useful things and not cosplay accessories.
ref 1
http://tvtropes.org/pmwiki/pmwiki.php/Main/SubvertedTroperef 2
http://tvtropes.org/pmwiki/pmwiki.php/Main/PlayingWithATrope