You don't
bowser has 92%
There are only 2 files in Mario and Luigi Bowser's Inside Story.
First complete the 'Joint Tower' area as Mario, then press R as Bowser.
There's no easy way. Just get a lot of EXP. A good place to get EXP for Mario and Luigi is in the Airway. A good place for Bowser is in and around Peach's Castle. I hope I helped you!
You can't do it with Mario and Luigi, but you can with Bowser. (You have to unlock it though) You press Y and then Y again when you're in the air. If you breathing fire, you need to press R. Then it should work. Hope I helped! :)
bowser has 92%
You go through the pipes in bowsers body
There's Save Blocks everywhere! Inside Bowser and outside Bowser.
You can go into Bowser's Castle when trying to get out of the path.
noone
bowser can breath fire!
There are only 2 files in Mario and Luigi Bowser's Inside Story.
Where are you, are you in the castle, have you found bowser?
You have to defeat a bug that's blocking Bowser's flame pipe.
First complete the 'Joint Tower' area as Mario, then press R as Bowser.
u hav to go into bowsers memory banks and u beat fake Mario and luigi then get the code
The Memory Banks should be in Bowsers head. When you can choose where you want to go inside Bowser, go to the Memory Banks in Bowser's head. (But you have to unlock the Memory Banks so you might not have it)