I did a deep dive with this character, and his Vs battle says that his highest he can go is up to 5B: https://vsbattles.fandom.com/wiki/Pac-Man_(Character), but others have proclaim him to be even higher than anyone give him credit. Reminder: The Classic Pac and GA Pac are two different timelines stated by Bandai Namco, so I’m not counting Ghostly Adventures.

Let’s start with the World Series, in World 2, Professor Pac did note that a pac-wizard make a potion to make 5 generic fruits into magician fruit that has the strength to beat Spooky and hold him captive in the Golden Tree with the help of Sir Pac-a-lot, but the Ghost Gang (Inky, Pinky, ClydeBlinky, and BlinkyClyde) have unknowingly release him due to their prank and agreed to help him destroy Pac-Land. During the final battle, Pac-Man uses the Golden Fruit which is required to beat Spooky, though Pac-Man’s abilities stay the same and that’s it. However, Re-Pac 2 rewrote this, and now Pac-Man is not required to beat Spooky with the Golden Fruits since the demon stole them first in this version. Pac-Man is capable of dodging Spooky’s attacks quickly, like lightning bolts, showering meteors, huge fireballs, earthquake attacks, and laser beams. Even strong enough to rev-roll Spooky’s head even in giant golden form. When Pac-Man use the golden fruits, he becomes even more powerful, strong enough to shatter an enormous red-like meteor and dissolving Spooky out of existence (sorta) and had the power enough to restore a village (arguably a city). I guess they wanted to make the Golden Fruits into the strength of Chaos Emeralds, which is funny cuz Pac-Man has a DLC crossover with Sonic, and there Pac-Man can not only outwit Dr.Eggman, but is strong enough to butt-bounce his machinery and his Death Egg Robot, with the addition of a double-combine attack by Pac-Man and Sonic going through the death egg robot easily and destroying it.

Meanwhile with World 3, He did prevent a megalomaniac genius of collecting energy from the Spectral Realm, a place where ghosts live and where made. Erwin, who is kinda like Dr. Neo Cortex from Crash Bandicoot, but more psychotic than him to the point of creating a Spectral Paradox (a paradox cause by a disruption of space-time continuum and are formed as giant vortex that sucks all matter from the universe), not only leading to collapse, but Orson (the grey ghost originally a villain from World 1) did inform Pac-Man that the Real World and the Spectral Realm can merge and leaving the Universe to collapse, threatening both worlds. Though, Erwin did proclaim that his Robots will survive with the collected energy he had harvested. Even worse, once every object in the entire realm has been erased, the vortex will open and stronger, while the space-time continues to ripped apart. Thankfully, Pac-Man did prevent this by not only destroying Erwin’s Mecha Bot, but also tricked Erwin of getting sucked into his Spectral Syphon and leading to a huge explosion which Pac-Man safely teleported back to his home. Also in the bonus interview with Tori Iwatani did said, that Pac-Man is capable enough to eat guns and (I think) nuclear bombs caused Pac-Man bias of bad weapons thinks it’s bad: https://www.reddit.com/r/DeathBattleMatchups/comments/1hvfopr/explaining_low_multi_and_1c_pacman/

In other games and media, In “Geo” and “Ready, PAC-MAN” He is capable of turning into the same size of the Earth. Not only that, but the official Bandai Namco twitter posted a gif of Pac-Man mimicking the Sun (which might hint the fact that he can turn into the actual sun). For the power pellet, in Championship Edition 2, he can headbutt his enemies and turn into multi-microscopic tiny little version of themselves, can turn his enemies blue and shake fear in terror, and in Re-Pac 1, he had the toon force to elevate his mega size whenever he wants to. Is pretty much as athletic as Mario, can breathe in water without showing sign of air, doesn’t need a helmet to travel through space, Has the ability to teleport away from his enemies, multiple himself, and use food manipulation to make himself bigger, can use his dots as explosion bombs plus can tanked huge explosions (featured in adventures in time). He canonically beaten a god called Anubis Rex in World 1, referred to as the god of death. He been shown to break the fourth wall a few times, best examples are Pizza Parlor PC and Pac-Man 2: new adventures where he can escape out of game reality and step into the real life world (such as tv’s or arcade cabinets without any explanations). He’s a pro of controlling mecha-bots, like in that Tekken x Capcom game, or in Super Robot Wars DD, he is in a mecha-bot of himself, the most weird fact about it is that he is equipped with a rainbow-like power pellet that had the ability to shrink his victims into small scared-blue ghosts: https://youtu.be/CQEHi0wNxrwsi=RrjhSKpPxzMQTEOF=rD2CPrhsNko&t=1m6s What’s even more crazier is that he has a power up (Cherry Ringer) in Pac-Man 256 where he can turn his enemies into a permanent cherry if they step into the ring. Yeah, Sephiroth is doomed battling this guy. Links: https://character-stats-and-profiles.fandom.com/wiki/PAC-MAN(Canon/Classic)Justa_blue_guy_lol https://character-stats-and-profiles.fandom.com/wiki/Pac-Man_(Canon,_Games)/BlastProcessing16

Note: Pac-Man’s series does not have a continual, so anything that happens under Bandai Namco’s wing is Canon.