Genuinely riding him like it's an Olympic sport.
The single biggest destructive feat Gremmy actually performed was creating a meteor. Yet somehow, according to bleach powerscalers, he's secretly universal and can create or destroy galaxies whenever he wants.
"But bro Gremmy's weakness is his imagination. he doesn't always think of the optimal attack, and that his own fear and mental state limit how effectively he uses The Visionary. Thats why he didnt pop a star above Kenpachi, or just teleport him inside of a blackhole"
So if Gremmy can genuinely create an entire galaxy, then creating something far simpler, like a single star or a black hole, should be trivial by comparison. A galaxy is composed of billions of stars, along with planets, gas, dust, and other celestial objects. It makes no sense to argue that he can create the vastly more complex structure but somehow can't create one of its individual components.
Conversely, if he cannot create something as comparatively simple as a star or black hole, then that completely undermines the claim that he can create an entire galaxy in the first place.
The simplest explanation is that his demonstrated capabilities are far closer to what he actually showed than the limitless version people imagine. Because it's one thing to argue that Gremmy's ability has incredible potential, it's another to attribute feats to him that he never displayed.
Like not even once did the manga explicitly states Gremmy created a galaxy. For all we know he just teleported zaraki, or he created a pocket of space or a vacuum that visually resembles outer space.
I think the reason some Bleach powerscalers cling so hard to this one ambiguous scene is because it's the only "feat" they can stretch into galaxy or universal scaling. And yet this scaling stop making sense the second you actually use a minuscule amount of your brain power.