There's a fine line to walk when making new mechanics. I think most of my characters have some unique system that isn't present at all in Brawl, but is rather based on something in Brawl (like the way Naota can "morph" into Canti, or how Dracula never falls down/air dodges/doesn't run/etc.).
And like KingK.Rool mentioned, 'Warlord's pretty prolific in that regard too, as are a few of K.Rool's own 'sets (in fact, almost all of the movesets I've reviewed by request have at least some sort of innovation to it). So really...I don't think 5 Special moves is a bad thing, since it's not a standard thing, and people won't lose points or be judged more harshly for not having it.
If you want to make things up, go right ahead--that's kind of the whole point. Just don't feel that you have to, is all. If you make something that we don't like (for theoretical example: a character with a Street Fighter-esque Super Combo input), then we'll tell you to shorten it.
tl;dr - The opposite of what 'Kibble said.