back to the main question, really dude, smash isn't addictive to everyone. Some people seriously don't like it as much as i wish it weren't true. if i play smash too much with my friends they get bored of it and moan and/or violently attack me at the very beginning syllable of suggestion of the game. really. this may be happening with ur brother. if so, consider how long a day you try to get him to play. if the answer is 30 minutes or more, try backing off a little. play DBZ a little, get better at that, play a game you can compromise on, or just go outside for a while.
After two weeks or so of this, try bringing smash back up. if he resists, point out that you've relented to his requests for DBZ and that you deserve a chance to play what you want. This is the part where you own him. hard. challenge him so much that he'll want to play more so that he can beat you again. this is my theory for what will work for your brother, this isn't exactly what works with my friends though. but try it, see if it works.