To all those who are wondering who will get a slot as a Pokemon representative in SSB4's tight roster, I present to you the Smash-Pokemon Representative Analysis System.
Popularity:
0 - This Pokemon is largely overlooked both officially and by Pokemon fans
1 - This Pokemon possesses a cult following
2 - This Pokemon is relatively prominent within the general fandom, or is popular by virtue of being related to a popular Pokemon
3 - This Pokemon has a humongous and lasting following that the Pokemon Company has been known to directly cater to
Iconography:
0 - The layman would not at all be familiar with this Pokemon
1 - This Pokemon is only recognizable to those more studied in the Pokedex, or was only temporarily symbolic
2 - People who pay at least a small amount of attention to Pokemon would likely be familiar with this Pokemon, or it is iconic by virtue of being related to an iconic Pokemon
3 - This Pokemon is eternally branded as a symbol of the series, and is instantly recognizable, possibly even by non-fans
Relevancy:
0 - This Pokemon is simply not a very large player in the franchise as a whole
1 - This Pokemon's time in the spotlight has passed, or has been given cursory attention recently
2 - This Pokemon is still acknowledged by, active in, or directly related to recent Pokemon happenings
3 - This Pokemon is getting top billing in marketing at this very moment
Pikachu - 9
Mewtwo - 9
Charizard - 9
Squirtle - 8
Lucario - 8
Ivysaur - 7
Jigglypuff - 5
Pichu - 5
You need a minimum of 5/9 to be feasibly added to the Smash Brothers series.