Remembering Anime/cartoon from around 10 years ago
It could potentially be a match for Ranma 1/2

It has a character named Happosi.  He's a step below "one of the main characters", so even though the show doesn't revolve around him, you'll see him often.

He's also not a child, He's actually really old, But It is possible to mistake him for a child because he's really short and he acts like one too.  He does look poorly drawn when compared with the rest of the characters.

This is what he looks like