User blog comment:ShonenChicoBoy/Shonen's Regimen and Tonic: April 2015/@comment-136273-20150417110210/@comment-136273-20150417161152

What constitutes an overpowered character in the context of Bleach fanon is, IMHO:
 * Emphasis on just how gargantuan spiritual power the character boasts.
 * Lack of any apparent weaknesses to exploit.

For instance, Hikari Maebure is my most powerful character. He can pacify Captain-class beings with his spiritual pressure and his Kido is extremely versatile, but he's got mediocre close combat ability and durability. If you weather the hail of magic nukes and get past his multilayered barriers to reach him, all he can do at that point is say "Well, shit."

Certain characters in FC seem to lack that crucial weak spot to exploit. It may be there, somewhere, for the opponent to find out, but other times it appears as if the author forgot to include one or two in their endeavour to describe that wondrously powerful Uber Badass.

Another, much more specific issue related to the subject matter is those two super-powerful Lieutenants I mentioned. We've got canon precedent for strong Lieutenants with Bankai in the canon, but why go the extra mile and claim that those two can trample any of the Captains? That speaks poorly of the author, to be honest.