Yes, it's a creative design decision with Pac-Man as stated by Sakurai. I believe it was a new addition for Super Smash Bros Ultimate since Heihachi didn't appear as part of Pac-Man's taunt for Super Smash Bros For Wii U/3DS. Similar to the creative design decision of the Fatal Fury series track listing contains songs from all across SNK's history (Fatal Fury: King of Fighters, The King of Fighters, Alpha Mission, Ikari Warriors, Athena, Psycho Soldier, Art of Fighting, Samurai Shodown, Metal Slug)
https://www.sourcegaming.info/2015/06/26/800/
Sakurai: The employees from Namco were surprised and overjoyed when they were notified of Pac-man’s inclusion. “I can’t believe you made Pac-man look this good!” they said.
Interviewer: Wait, so you didn’t include him just because of the Namco connection?
Sakurai: Pac-man’s design was updated in a 2013 CGI cartoon titled, “Pac-man and the Ghostly Adventures.” This new design has been used in a variety of products. But in the end I felt that his old-school design was better, and used that in the design plan. If that was rejected, I thought about dropping Pac-man altogether.
Interviewer: I really like how even his movement is full of references.
Sakurai: You might call him a hybrid, but he’s not just Pac-man– I think he ended up also representing all of the great parts of Namco as well.
Interviewer: Between Bandai and Namco, were there any other strong candidates for inclusion as a fighter?
Sakurai: There were none. We basically thought of all the characters at the start of development. We decided on characters we knew we could make. However, there were a few in consideration, such as Heihachi from “Tekken.”
Interviewer: Heihachi!
Sakurai: That’s right. However, implementing Heihachi’s movement in Smash would be difficult…