IMO, Smash Bros. is one of the most in-depth games I've ever played...so much in fact there is even a whole glossary devoted to the game. Clearly there is a difference between pros and inexperienced players...and button-mashing doesn't help either. Smash tests reflexes and a bit of decision-making. You can't become a pro in a mere few days, either...just take a look at some of the videos on Youtube that display matches played by pros.
There's enough depth in Smash to warrant its own (many) series of tournaments.