I'm pretty sure Matt scales above that since he scales above 3 characters and not just 1. Matt can resist reality warping on a Low 2-C scale as well thanks to The Glitch which could be stronger than the Cosmic Gigalith but is a vague character in general
Matt can also summon NoLegs who can summon the avatars of Godcat which stomped and blitzed the EBF4 party 2 times in a row, and conceded (because they realized how humankind wasn't worthless, not that they couldn't beat them) the 3rd time. NoLegs can get rid of any stat amp with Star Blast. He can also give Sonic Bad Luck and Tired, a status that makes the victim's attacks easier to avoid and makes incoming attacks harder to dodge.
Matt can also inflict Syphon with other summons, which disable all types of things that could be classified as "skills", even things such as Matt punching via Unleash and Steal Item or doing physical sword slashes like Quick Slash and Revenge gets disabled and many enemies' only option is to do nothing, surrender or be forced to use weak, nameless attacks. All summons scale to Matt as he had to fight them in order to get them