Weell, my most RANDOM inclusions, I had to say that are:
-Captain N
Because this guy, to me, is the figurehead of Nintendo cartoons. Nintendo has had several TV shows since the late 80's/90's. Super Mario Bros. Super Show, Legend of Zelda, Captain N, (they were a trio by DIC entertainment), then Pokemon, the most successful one so far, F-Zero and Kirby anime, and some Donkey Kong shows as well.
The only one NOT present in Smash Bros. is Captain N. And it would mean a LOT to me if one of my favorite childhood Nintend cartoons made it in. And since Captain N was made by a NINTENDO employee, he's technically a 1st party comic/cartoon character.
-Nester / (Lark in Pilotwings)
Almost the same case as Captain N, but his comic book counterpart. He was the mascot of Nintendo Power magazine. He had a segment in the magazine called "Howard and Nester" which featured a brief story about them inside a random videogame, where they would provide hints. But most of the time he had some crazy plan backfiring on him, and making his rival Howard look better.
These two could get in under the same conditions that R.O.B. got in. R.O.B. was a toy, later turned videogame character. Nester at least has been a videogame character in two incartnations, 1.- Pilotwings when he was named Lark. And 2.- in a Virtual Boy game called Nester's Funky Bowling.
Captain N has appeared in a Cartoon and Comic book.
Both Nintendo properties.
...
If I had to choose my 3rd and last random inclusion... Michael Jones from StarTropics. He s so unknown, that he could basically be considered a really random inclusion.