A variation on duder, a dude-ler is simply a dude. He could be your homie, your pot dealer, your neighbor, or he could be some guy you just met. A dude-ler could be any guy. Often, it is used as a term of endearment between male friends. It does not refer to females, usually.
Hey, dude-ler, wanna go disc golfing, and smoke a bowl on the bowl hole?