Here's the thing. Sakurai has not made the effort, as we can see, for Pokemon as a series in Smash Bros, to represent every single generation. Really, why WOULD Sakurai do that? If he were to try to do that now, then it would take him several games. The current Pokemon Trainer has the most iconic starter Pokemon, and when it comes to Smash Bros., he isn't just going to throw in three no names.
Generation 1 is special because it started it all. If he replaces the Pokemon Trainer with a new one, thus adding 3 movesets, it would set a precedent to add a whole new team. Every. Single. Game. That would be development time wasted on a character that is better off left alone.
For Smash 4, we're getting a smaller amount of newcomers. If you really think he's going to have his team spend extra time changing a character simply for the sake of staying current, then you're getting your hopes up.
Representing every generation is not a requirement, nor is it something that appears to matter at this point. The different generations can easily be represented through other means, like Pokeballs, and stages.