Its impossible for me to play it since we dont have official Nintendo stores here and no one downloads it (Nintendo is known for its NES here) so there are no chances to playing it, thats why I asked you guys whats the joy in that fighting game that you apparently (?) do not find in other fighting releases.
Okay, I'll try to give you an explanation, since I'm bored
Here goes:
First of all, people like to have cool characters to fight with. Most people always pick the cool characters in fighting games first. Characters which stand out for another like Ryu and Ken in Street Fighter, Scorpion and Lui Kang in Mortal Kombat etc.
In Smash, you basically have all the cool characters a nintendo fan could ever dream of.
To give you an example, Soul Calibur II was released on 3 consoles, all 3 with a different character fitting to their system. As you probably know, Gamecube was far behind the other consoles in sales, it was in deep shit and a lot of stores even gave up on it due to bad salesment. However, the GC version outsold the other 2 versions on PS2 and Xbox by far! How come? Link was in it. People actually bought a gamecube just to play with Link.
Now take Smash Bros. It is FILLED with cool and popular characters, especially for Nintendo fanboys. That makes the first important reason why to like this game.
The second one, is due to it's different combat system. You don't have HP here which slowly deplees the more you get hit. This fighter is all about survival, rather than combo's. There are items which increase your chances in both offensive and defensive ways, which makes up for an all new experience in fighting games. It's not as deep as most fighting games, but it doesn't want to compare itself to different fighting games. This is a whole different game.
Comparing it to a fighting game is like comparing WWF Smackdown to Dead or Alive. You can fight in both games, but there's a whole different dimension to both of them.
That doesn't mean there's no depth in it at all. It's not for no reason that there have been held a lot of competitions for this game. Underneath all the simple mechanics, there is still a massive strategic element to be found in this game. Just like with the pokemon games, you can just train, complete the game and catch a few pokemon. However, pokemon also has the pokemon nature and EV points for example, which influence your stats and can make you the best. Smash Bros has a different system of course, but at least as hard to master and become a really skilled Smash Bros Player.
Smash Bros isn't really meant as a competitive game, like most fighters. Smash Bros is all about fun. Fun in both single and multiplayer (up to 4 players), without closing all space to make it into a competitive games. You can tweak all option like items, which ones to show up and which not. Speed the game up or not and many many more. You can make it as competitive as you want.
I think that sums up the magic behind Smash Bros. Please keep in mind that english is not my native language, so I might have used a few wrong phrases