I'm just looking for opinions on this. Multiple Madness for the non-GC comes to mind, but I'm too tired to think through all of them right now. And I know @
Lockhart has some serious beef going on with Shiznit/Dissizit and would gladly nominate him for the latter, but I'm pretty sure that (objectively speaking, in terms of battle skill) the worst GC would have to be the first one, SpleNDiD in 2006 (no h8).
EDIT: I'm counting all battlers ever on LB, not just active or recent/modern ones. I also mean both in terms of objective skill, and skill relative to their time (LEFT FIELD, for example, was top-tier in his day, but his bars are just decent to a modern reader).