In EarthBound, plain text is mostly ASCII shifted up 0x30. For example, a space, which is 0x20 in ASCII, is 0x50 in EarthBound's text. A few characters do not exist EarthBound's font and are replaced by characters which are used. For example, < and > are replaced by left and right quotes respectively.
Also, in enemy names | (a pipe) gets replaced with the first character's name. This may occur in other places as well.
All other text formats in EarthBound are plain text with added control codes below 0x20.