Is lucas ness's brother

Answer 1

Of course not. Lucas and Ness are completely different protagonists from the Mother/Earthbound series, and have absolutely no relations. Ness only appears in Earthbound (Mother 2), while Lucas appears only in Mother 3 (or Earthbound 2). In Mother 3, Lucas already has a brother (a twin brother) of his own, known as Claus.

Since Mother 3 was never released out of Japan, it definitely expresses the confusion when both characters appeared in Super Smash Bros. Brawl.

If you don't believe me, go to http://mother3.fobby.net/and play the Mother 3 Fan Translation yourself. You'll need a GameBoy Advance emulator first.