SRS BSNS post:
I would add to the argument that it isn't guaranteed that we'll get a 5th gen newcomer that Melee could a reason why. People at first are gonna be like, "What that's silly that would actually prove the opposite since Pichu got in", but when you take a closer look at things, then you'll start to see what I mean. Pichu is a 2nd gen Pokemon, yes, and 2nd gen was the newest gen during Melee's time, yes. But he didn't get in because of that. He only got in a quick Pikachu clone and one-time joke character due to time constraints and Sakurai wanting to artificially increase the roster size. Not due to being from the newest gen. So, since he didn't seem to consider putting in any other popular 2nd gen Pokemon (like Heracross), had Sakurai and company not decided to beef up the roster at the last time with a bunch of clones, we seriously would have only gotten Mewtwo in Melee (watch someone say, "LOL THIS IS ALL HYPOTHETICAL CRAP WE STILL GOT PICHU IN MELEE REGARDLESS").
Also, people have to realize that playable status isn't the only way to represent Pokemon on the battlefield. We have Pokeballs to represent the numerous Pokemon we've come to know over the years. After all, that's exactly what happened with 3rd gen in Brawl. Did we get Deoxys or any other 3rd gen Pokamanz as a playable character (no Pra_Mai/Plusle and Minun/whatever being "planned" doesn't count)? No, but we still got a whole bunch of 3rd gen Pokemon as Pokeball Pokemon. Who's to say that won't happen with 5th gen in Smash 4?
So... yeah, that's muh two cents
*goes back into the shadows*