i dont know how applicable this is, but so i was playing this guy on for glory for like 17 games, each one being last stock last hit (outside of a circlepad related sd or two), so i think we were evenly matched. at about game 17, he picks ness, ness being his pick in the first match so i assume he is a regular ness player, and i happened to pick kirby (kirby being a character i rarely play only for certain matchups).
That match, I 2 stock him incredibly quickly with inhale gimps and he immediately disconnects. if you can fall on him with an inhale during the ending frames of his dash attack or something and jump off, then when he mashes out, ness is probably the easiest character to complete the gimp on. between your dair and footstool vs ness's slow double jump and slow (and still interceptible i assume) pk thunder II, inhale-walkoffs are mounds of useful vs ness. dont miss the inhale though because if its anything like kirby vs ness in project m, his smash attacks all outrange inhale. also none of ness's projectiles force kirby into projectile-swallow stun so, assuming his smashes DONT outrange inhale, while he cant use pk fire to swallow-lag you and then get a clean f smash or somethin, he can still probably just get a regular pk fire hit and then grab/dash attack/whatever pk fire follow up ness does in this game.
other characters that are very susceptible to inhale-walkoff gimps are cfalcon with his easily dair'ed up-b, fox with his fall speed and the dairable startup time on firefox, and i assume dk with his poor vertical recovery on dk tornado. ive yet to try it on yoshi, maybe that would sooth the matchup a bit. most other characters you just want to spit off though for the damage because they'll usually just mash up-b right through you.
i hope this is useful information lol