Another thing that many people overlook is the fact that, if you're struggling because it's so hard to get to tourneys, this could mean that tourneys aren't close enough to you. This probably means other people near you suffer the same problem. To solve this problem, there's a simple solution: host a tourney in your area. If you properly advertise it in your area, it will should garner attendance, unless the smash scene in your area is dead.
Being 12 is rough trying to host a tourney, so you should get the help of an older family member, or even olde group of Smash players who can help you with it. You should find ways to communicate and contact the surrounding community, and see how many people you can get to come out and play. Brawl is a very popular game, and casual players might go out and play just for fun if they can afford it.
Talk to other tourney directors and venue hosts for more information about how to go about hosting a tourney, and see if hosting a tourney in your area can solve your transportation problem.