"There are all kinds of game genres, like fighting games and puzzle games, and each one has its own 'fun core.' First, I try taking away everything unnecessary around that core. Then, it's like I place the fun core somewhere else and build around it again." - Masahiro Sakurai
In my opinion, Sakurai has perfectly nailed that 'core' of fun. Not many other games have core elements as strong as his, nor do they have the insane level of polish. Obviously, the Smash Bros. series is known for that. Sakurai explains what desire within him gave birth to Smash Bros. back in the days of the N64.
"I wanted to offer an alternative to the two-dimensional fighting games that were crowding out the market. I also wanted to see if it was possible to make an interesting four-player game that offered a new experience every time you play. Simply put, I was aiming to design a four-player battle royal."