The developers initially considered replacing the character Ness with Lucas (the protagonist of the Japan-only GBA title Mother 3), and planned on making Marth and Roy Japanese-exclusive fighters. However, Ness remained the spokes-fighter for the Earthbound trilogy due to consideration for delays in releasing Mother 3, and Marth and Roy were made available worldwide due to fans' desires to play as the Fire Emblem duo.
Contributed by game4brains