I don't think Mxy was lying either. Manhattan(before we knew it was him) was being hyped like a motherf*cker in the years leading up to Doomsday Clock. That said, Mxy has on-panel feats that no other character(in all of comics) are likely to ever top.
But per current DC cosmology/continuity, Mxy is technically still not at the top of the totem pole... So in that respect, it's always going to come down to: "lip service/accolades/implied power vs. displayed feats" -- Mxy is [probably] always going to take the latter, but not necessarily the former. /shrug
I don't know if the writer is trying to be sarcastic or not, but the reaction of Jackson when he hears Orion loves battles makes me lol
Battlesexual, LMAO.
https://ibb.co/ZVVSR0y