You mean Ness or Lucas? Personally, I think both boys do equally well against the larger characters, although I prefer Ness against Dedede and Lucas against DK. Ness's PK fire has cool potential against the waddle-dees, since you can get the fire pillar to execute without actually hitting your opponent. Lucas's can do that too, of course, but it's not nearly as cool. In DK's case, I think Lucas's faster moves are better for poking him out of his attacks. Still, I think either boy is a good match-up for big characters.
Also, absorbing Waddle-doo beams = <3
I should prob'ly update this old thing ...