The problem many people have with Mario, including myself, is that he's too rounded. Not fast, not heavy, not powerful, just somewhere in the middle. He has a fee good attacks, like his f-air, which spikes, but against any good opponent, it's nigh-impossible to hit. His n-air is good for leading into other attacks, and his b-air is quite good for edge-guarding. His d-throw to u-tilt is good for racking good damage to most characters. Besides this, he has very few good options. That said, if you don't play competitively, then it doesn't matter who you play, as long as you have fun.