One of the limitations that comes from the Nintendo DS itself is the screen resolution. To put it simply, the Nintendo DS does not have a big enough screen to play Super Smash Brothers decently. Have you ever tried playing Super Smash Brothers on a screen as small as the one on the Nintendo DS? When the camera zooms out, it is damn near impossible to tell where you are and what you are doing. The resolution would defiantly be one major limitation that they would have to find a way of working around.
Easily solved. Don't zoom out. The stages can be made to be small enough and the bottom screen can sport a "map" of sorts. Also, other players can be indicated by an arrow.
I think you all fail to realize that Super Smash Brothers is not only a single-player game. Are you all honestly telling me that you all want a Super Smash Brothers game that is designed specifically to play it by yourself?
I think you fail to realize that the DS is not a one-player only device. Like others have said, there's more than enough ways to not play by yourself. There's WiFi, multicard local connection, and single card local connection that the DS can provide. I think you weren't around when Super Mario Kart DS and Metroid Prime Hunters came out, really.
I don't understand why people place so many invisible limitations. The only limitations are time, money, space, and interest. That's all, really.
