Ness is the young protagonist of Earthbound, hailing from the town of Onett in Eagleland. He’s a huge fan of baseball and typically wears a baseball cap, and even attacks with a bat. In addition to using ordinary objects as weapons such as his bat or yo-yos and slingshots, Ness is also skilled in PSI.
In Smash Bros., Ness uses PSI for all of his special attacks, although in Earthbound it was is party members that used them, not himself. He tends to yell the names of his PSI attacks when he uses them for unknown reasons. It's quite endearing, actually.