It's difficult to provide any concrete feats given what his role generally is in a comic book(being a neutral observer most of the times).
However, in a fight with Aron the Rogue Watcher, the 2 waged war "across infinite rivers of reality", which ultimately ended in Uatu converting Aron into pure energy. The same Aron who beat Molecule Man without much trouble(although Owen was unable to control organic molecules at that time).
That is almost my point (the Aron feat non-withstanding, that is pretty badass), for as many low feats that Apoc has, is we go by highest showings, he is actually really strong.
I'm not saying he should beat Utau, but in terms of forum rules and feats, etc, he might just have better showings based on more appearances/different character type.
