I'm going to be really critical here...
Your technicals are good, but your fighting style is sloppy. You're furious and hectic, when the best that Ness can be is reserved and precise. The fact that the you survive some of your mistakes seems to be entirely your opponents fault.
The style you play is more fitting to a character who can accumulate a lot of damage without worrying. Heavier/stronger characters can match blow for blow and end up in the advantage, because they are both hard to KO and deal lots of damage per hit. Ness is neither heavy nor strong though. He needs to hit more than he gets hit, or he will end up with more damage and die before he's anywhere near the % he needs to KO.
On the subject of Ness's weak KO capability, your edgegaurding is one fairly simple thing you could improve to greatly increase your KO count.
Having said all that, you're definately going in the right direction, you've got all the skill. Now just work our your strategies a little bit and you'll be top notch. Defense, combo, edge guard, and recovery. Put your attacks right where they're supposed to be and you won't need to attack so much.
