Super Smash Flash 3 is often called the Super Smash Flash 2 v0.9. In fact there is no SSF3 version available yet, because the developer is working on creating the full version of SSF2 right now.
Super Smash Flash became the most popular fighting game soon after release. The main reason why its so popular is that there are a lot of characters in this game and all of them have different powers, different attack skills. The characters are gathered together from the popular games and cartoons. For example Pikachu, Megaman, a Contra Guy and others.