Is it safe to replace an Image with FF using a hex editor if I know the exact number of bytes?
When I use another border block in Palette town specifically the black empty tile, it turns like some glitchy blue wavy tiles. Why is that? How to fix?
1) Open up the tile viewer and find the sprite. See the location it is in the memory, now go to that location in memory viewer and search for the bytes you find there in a hex editor.
2) Yes, as long as nothing trys to use that image after you erase it, but still be very careful.
3) That isn't a black tile, it is a transparent tile. You need to find an actualy black tile. (I'm not sure if Palette Town has one, but many maps do.) Also, you could try making your own black tile.