The nostalgia...I remember being an innocent 6 or 7 year old OBSESSED with Mario, and this game had Mario in it, and so I played it. And I ended up LOVING it and discovering lots of other characters rather than just Mario...good innocent times. And I still play this sometimes because ogf the nostalgia. But this right here is a REVIEW, and not a nostalgia rush. So let's take our nostalgia glasses off and get ourselves together!
Overall, I give this game a 2.5/5, which equals average, aka, not good, not bad. The good things about it: It has lots of different characters from all different series', all with their own unique powers and abilities. Playing through Classic, Adventure, All Star, and the multi-man modes are all fun.
Now for the flaws: The biggest flaw and the most obvious one is that there's no skill at all involved. You can easily beat a match by just going left/light, while holding one button. The characters just slide to the opposite side of the screen. And stage 3 of Adventure mode is a chore because of so much lag. And there are sometimes glitches, like where the air hits you and makes you fall. And what is up with the 2 poorly made Sonic fan-characters (Blade & Blue)? Even Pichu would've been a better edition than those guys.
And that wraps it up. But Cleod-9, you were a young developer with no experience when you made this, and for someone like that, this game is incredible. And your sequel Super Smash Flash 2 is just amazing. Just flawless. The only bad thing is the Online Mode: Doesn't remember username and pass, matches always disconnect, screen always blacks out, there's sudden death, match lags, etc. But those problems will be fixed in the future. Just keep up the good work.