ok if you are talking about the new Super Mario bros ds game, you have to defeat the world 2 second boss (petey plant) as mini Mario/luigi
Chat with our AI personalities
All i know is that the mini mushrooms are in world 2 boss castle(to unlock world4) and world 5 boss castle(to unlock world 7) you have to beat the worlds 2 &7 boss when your mini Mario, in order to unlock worlds 4 & 7, it will be a little difficult beating the bosses when your mini Mario but it's worth it
Ok so on Super Mario Bros for the Nintendo to get to world 4 you have to go to world 2 and defeat it as tiny Mario then to get to world 7 you have to go defeat world 5 as tiny Marion there that is how you do it
in world 1 at the tower there is a red flag that you need to get to unlock the cannon.
you unlock it 3-4
I cant completely remember, but if you have to defeat a sand caterpillar at the end of one of the desert levels on world 3 (i think its world 3) you have to kill him in a certain way to unlock world 4. Its either world 3 you do that on or world 6 to unlock world 7. I think you have to jump up above his head and slam down on him to kill him. I never did this myself but i was shown by a friend, I only kind of know one so sorry about the other world. Sorry if it doesnt.