In the original makes far more logical sense, though. In 1999, Pokémon was really hitting on all cylinders, and Meowth was easily in the forefront of the series thanks to the Animated Series. The 2nd Generation of Pokémon was released in 1999, the same year as the original Smash Bros, and seeing as Smash Bros was already in development prior, they were dealing with the original 1st Generation only. So Meowth was an easy candidate, especially to coincide with "rival" Pikachu, in the Animated Series.
My statement wasn't anti-Meowth being included(he's actually always been my favorite Pokémon, coincidentally enough lol), it's more of a statement on that it just wouldn't seem likely that he would be included NOW, in 2014. Not with 6 Generations of Pokémon, a far exhausted Animated Series, far removed from the original seasons we grew up on 15 years ago...