in the new Super Mario bros Nintendo dual screen what i did was get the mega mushroom before i entered the final castle. When i finally met up with bowser at the end i used the mushroom ( after crossing though a small dor because if you use the mega muchroom before that you get stuck ) and plowed through everyone there. It works well but maybe there are other ways to beat it too.
browser
defeat it with bombs
you can just use fire flower
Either jump on it or throw something at it.
Defeat Petey Piranha (W5 Boss) as Mini Mario.
You need to defeat Petey Pirhanna as mini Mario or mini Luigi.
Fireball or jump on the pokeys head
defeat the boss from world 2 and 5 with mini Mario
you just jump on his head....whenever he isn't in his shell........
super Mario bros 3 is ten times better than super Mario bros
Defeat the boss at the end of W2 as Mini Mario. A Mini Mushroom can be found past the checkpoint flag.
as tiny Mario defeat world 2 boss than you will go to world 4 problem solved <=)