In order to get to world 4, you must beat the boss in world 2 with mini mini mario. In order to het to world 7, you have to beat the boss in world 6 with mini mini mario. hope i helped you
Ahh yes this one i was wondering about myself but i found out luckly i found out :) so actually its quite simple all you have to do is bit boswer jr in the castlein world 3 and 5 :)
In the Nintendo game you have to beat the boss on World Three with Mini Power (little blue mushroom that causes Mario to shrink).
you have to defeat the boss in world 5 castle with mini mario.
you have to complete the last castle on world 5 as mini Mario :) have fun !
Beat world five's boss as mini Mario/Luigi.
World 7
beat world 6
beet world 5 boss as mini Mario
Beat world 6 or 7.
die
restart the game
you can by playing hard
If you are referring to New Super Mario Bros., you can get to world 4 by defeating the boss(end boss, not koopa kid) as Mini Mario or Mini Luigi.You can also access world 7 in the same way from the boss of world 5.
For world 4, beat world 2 boss as Mini Mario. For World 7, beat world 5 boss as Mini Mario.