Also Google said,
it's highly possible that Pacman is registered as trademark. In that case anyone who would use it's depiction without permission can be sued. Though it depends on the degree the new character resembles the original Pacman and what the new character's created for, but all of this would
have to be proven in court if the copyright holder won't appreciate the parody.
I just assume that it's risky and may require more actions rather then just draw a picture.
Or someone could just send them a letter asking for permission - in which case you have absolutely no copyright issues.
Because there is nothing to guarantee that someones original design that they are submitting doesn't resemble an existing design and therefore infringe copyright or trademark.
From what I have read is that they were granting people the rights to use the characters - so a letter stating that it can be used (Even though it would fall under fair use as a parody) would be the absolute safest option.