it depends on what you wanna do. if you wanna beat the game, then you don't have to collect ALL of the stars. if you wanna use the cannon outside of the castle, then you require all 120 power stars.
TIP: There is a little surprise for you on top of the castle :)!
In order to start collecting Green Stars you will first need to find and collect all 120 normal Power Stars, you then need to finish the game by beating Bowser again for the Green Stars to show up.
You need to collect 5 stars. You collect 5 stars by doing challanges from Chris.
Eventually, when you stand in front of Rosalina on the Comet Observatory there will be a number. This number shows how many power stars you need to collect. When it hits zero...
i think it depends on how the stars collect the energies they need...i hope it help
You will need to collect all 150 stars and the cannon in front of the castle should open and then all you have to do is go in the cannon and blast off.
To fight Bowser for the last time you need 80 stars or 70 stars. To complete the game you need 120 stars.
any number of stars with luigi or all 150 stars
you need to collect every single star.
Although there are 150 stars in total, you only need 80 stars (and Mario) to complete the game as this is the number of stars you need to get into the final Bowser level.
you need to collect all of the 150 stars and that's EVERY single one and after that fight the final bowser and beat the game again and there yo go its open
It's by the water to the right of where you start, and it's surrounded by gray stone. (You also need to beat bowser)
If you get 120 stars then you can play with luigi. And then you need to find the 120 stars again but then with luigi!