PK Fire can be risky when you use it right next to an opponent. If you did hit with PKF, I would dtilt or fsmash. You landed some close PKFs, but you grabbed instead of any of those. That's fine though, grab after PKF is the most reliable. The others give more damage. Also don't use your bthrow at low percents, you gotta keep it fresh so it can kill easier.
I also wouldn't use dair in the the middle of some aerial combos, keep using quick moves so your opponent can't attack/airdodge out of the combo.
And good use of PKT2.
I didn't see any jabs or tilts, although Ness's jabs/tilts aren't anything special, but you should use them.
Utilt sets up aerial combos and can follow up by itself at low %. Also has a wierd disjointed hitbox.
Ftilt is an average get away from me move, but it can kill at 150% when its tilted up.
Dtilt is pretty mindgamey, has lots of follow ups, and racks up damage like crazy. Can't forget the dtilt fsmash combo! :D