I have a problem with lava bubble, swith and fireball palettes. I don't know which one uses enemy B, R, W, or the _ one. I tried replacing swith texture using enemy B but in game fireballs are pink and lava bubble colors are wrong. I also tried to replace every palette but i have the same problem! Pls help ?

I'm not sure I understand what exactly is your problem so I'll just explain everything.
1. Open all of the files listed in this thread all at once: https://nsmbhd.net/thread/4427-list-of-bitmaps-which-use-the-enemy-palette/, as well as all of the enemy palettes.
2. Press "Export all bitmaps with all palettes".
3. In an image editor, delete all of the garbage (the graphics that look corrupted because they're on the wrong palette).
4. Still in the image editor, replace all of the graphics you need to replace. Press the save button.
5. In NSMBe, press "Import all bitmaps with all palettes".
6. Press save all, you're done.
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Nothing to say, so jadnjkfmnjamnfjkldnajfnjkanfjdksan jsdnvj m.

Thanks ?, but i fixed replacing the corrupted palettes with the original ones and, when i had to replace a bitmap, i clicked on 'import this bitmap with existing palette' and it works! It can be useful for people who had my same problem ?

that works too, but you will be limited with the colors of the original palette. my method allows for completely custom palettes.
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Nothing to say, so jadnjkfmnjamnfjkldnajfnjkanfjdksan jsdnvj m.