Since there isn't much Ness discussion going on, I'll give some input
Jab- Brawl, with better Jab Cancel
Dash attack- Melee PK Push, but reversed. First hit sends vertical with decent kbg, second hit links into third, and third it a weak semispike
Ftilt- Brawl
Utilt- Smash64
Dtilt- Smash64
Grab- Make standing grab better. Brawl dashgrab
Fthrow- Melee
Uthrow- Melee
Dthrow- Brawl
Bthrow- Brawl
Fsmash- Melee
Usmash- Better- I believe you already know what to do with his Yo-Yos
Dsmash- See Above
Nair- Smash64 sexkick
Fair- Whatever is done, be careful obviously, lol. I suggest making the final hit angle low enough and have enough bkb so that it doesn't link into anything. PK Push is supposed to do just that, say GTFO to an opponent. Don't don't don't don't make its range bigger.
Uair- Melee
Dair- At the risk of sounding obvious, Smash64
Bair- Brawl
B- Melee power, size, auto detonate on ground, and control, Brawl startup and movement range- NEW- auto detonate on hit
Up B- Brawl, Melee single hit juggling tailwhip, path doesn't shorten if he hits something with PKT2, can thunder barrier, NEW- speed up and control made tighter to compensate the higher speed
Side B- Brawl Minus's 1.6 ground jump cancel, NEW- pseudo landing cancel (About half the landing lag)
Down B- NEW- 1 frame start up, 23 frame minimum "holding magnet out", remove wind, weak electric hit upward on release lasting 1 frame, 6 frame endlag on release, [total minimum frames- 30]
Attributes:
Run speed: Smash64
That's all I can say on the matter of Ness. Maybe simna can shed some more light on individual moves like his ground A attacks.