Fat Buu one shots. Mismatch.
Pikkon seemed to be near the level of Goku in other world after Cell. Goku trained for 7 years and possible could or could not defeat Fat Buu. That's with upgrade to make it easier for Goku. Pikkon does not have that upgrade so he would still be a lot behind. For me, he would easily be eaten by Fat Buu after a severe beating.