Part of what makes Smash Bros. so great is that it pits characters from all sorts of different franchises together—naturally, fans have ideas about what characters such be included. Like kids sending letters to the North Pole, tons of people take to Miiverse and write letters to Masahiro Sakurai, the creator of Smash Bros, in the hopes that he'll read the note and do what they ask.
The "Please Sakurai" Tumblr compiles a lot of the Miiverse posts where people beg Sakurai to include characters. Some of the suggestions are jokes. But some must genuine—and it's kind of sad, because Sakurai has made it clear that the development team picks the roster well in advance.
Here's a small selection of the sorts of posts the Smash Bros. Miiverse is full of:
You know what they say, though. Never say never. Plus, it's easy to make fun of this stuff but if my hunch is right—a lot of the folks doing this are kids—it's hard not to be heartened by the fact that they really, really love this franchise.
Still, I wouldn't blame the development team for not wading through all the posts. It's a bit much!
no but seriously tho sakurai pls put in Goku