Just get a lot of EXP. I heard the best place to do this is in and around Peach's Castle.
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)