Please, how can one bowser defeat three!?
If you really want to do fire vs fire, use Roy (BUT NOT MARTH!!!)
See, Roy is way better than Marth. Roy's UP B is not only stronger and cooler than marth's, but it sets the person you use it on ON FIRE!! THIRD DEGREE BURNS OUCHIES!!!!
Also, Roy's charge B is WAAAAAAAAAAAYYYYYYYYYYY stronger than Marth's, it can kill people 1000% of teh tiem!!! PLUS THERE'S AN EXPLOSION MORE BURNS FOR LOSAR BOWSERS!!!
but his best move is his down B, if bowser tries his fire YOU HIT HIM BACK WITH 10 TIMES MORE FIRE AND A BURNING GRAVE!!!
The only bad thing about Roy is that his sword is bigger than Marth, meaning he's obviously trying to compensate for something. It's alright though, because it gets MORE RANGE THAN BOWSER'S DEADLIEST OF DEADLY MOVES, the GUARANTEED HIT FORWARD SMASH!!!!
I think that should about cover it....oh, if you're ever losing but will do anyting to win, use your throws. It makes the Bowser spin around in the air so he's all dizzy and confused, it's cheap I know, but PLAY TO WIN!!!