As I see it, there literally isn't a character to go with this icon, any character from a game on the DS would represent the game series they come from, not the DS itself (all other characters are represented by their own franchises, excluding those ATs who fall under the Misc category that is the Smash Bros icon). Miis are a Wii element and have absolutely nothing to do with the DS, so it wouldn't make sense to give them the DS logo when they should have that of the Wii. The only reason why PictoChat has music from the Wii is because PictoChat, the program itself, has absolutely no music, and so songs from others games and franchises were selected because they would fit the stage's style. It's like the Balloon Fight song being used in the stage for Ice Climber, Balloon Fight and Ice Climber are entirely seperate, but the BF song was still used in the IC stage.
As for Animal Crossing, this doesn't confirm or deny a possible fighter. This doesn't mean anything but a stage can exist, have an icon, and still not have a character, which does make the idea of AC having items, stages, and a logo but not a fighter even more reasonable. Personally, I don't see any character plausible from AC to get in, with all of its important characters being part of the stage's background or an AT, but it's not impossible for it to get a fighter.
As for the icons, I don't see 21+ all being franchises without characters, but rather everything past 14 being new to Brawl, and can either contribute or not contribute a character despite where they land in the order.