Don't use your second jump onstage, especially if you're on FD. It's just super predictable as to where you're going to land and almost impossible to come down safely. You have a CHANCE when using Bair or Dair AC'd on shield, but otherwise it's just a big guessing game as to where you have to go and, for your opponent, where you WILL go. Most good opponents and characters can just restrict a majority of your options so that you have to come straight down. On some characters, you have a couple times where you can PKT2 downward (at an angle) toward a ledge and be safe, but only if you a.) don't overshoot it/the stage and b.) aren't directing it at your opponent's shield (edge of shield is fine, directly into opponent isn't). You can also use PSImag to delay time of descent. Basically, play with your opponent's head and make them guess on when you are going to land, but land differently each time or land in a way that best suits a situation.
If you are moving away from an opponent who has a shield up, you can go with a retreating dropdown bair (must be timed perfectly so you land immediately after the hitbox comes out) on shield and either get a poke or just land safely. I've done this a lot. If your opponent grabs at the right time, you may be in trouble, so vary between aiming at the top edge of the shield and the bottom edge.
Dropdown Dair AC'd only works if you can manage to land at their back. If you can, it's "who can react quickest?" and use the quickest move to punish the other. Too risky on shield, but in a general sense it can work against an opponent that is partly in the air or not able to perfect-shield soon. Follow the AC'd Dair with a grab or jab or dtilt or ftilt; utilt MIGHT work, but it's often too short on range to hit the opponent, so don't risk it; d/usmash don't work because they already have their shield up.
PKT2 to a corner IFF the opponent has used their last non-upb jump and can't hit you with anything. Key part is can't hit you with anything. If they CAN, it's pointless.
PSImag to halt above them then FF down with an aerial or airdodge. Time it so that they can't hit you with anything from their current position without moving too drastically.
The normal method is to just use an aerial or FF when going down, but Fair is TERRIBLE when falling (it doesn't hit low at all if you are FF'ing) and the opponent can see it coming easily. A good opponent will know to grab you on the spot and just say "HAHAHAH! I'M DESTROYING A CHILD'S DREAM!"
Keep the whole "must get back to the ground ASAP but opponent is there" situation to a minimum; Ness is good in the air, but being too high isn't ever good. Half of Ness' aerials require close proximity to ground to get their best and full usages.
YOU TRIED TO GRAB FOR PUNISH WAY TOO MANY TIMES!!! OH MY GOSH!!! Never do that. Grabbing to punish only works if you dashdance or pivot grab into it. Ness' standing grab is garbo. I always just FH Nair OoS because it hits both sides, is relatively fast, and has good priority in some sense. It's only around 10% on average, but it beats getting hit by something randomly. You can also SH Bair OoS if you have enough time to punish. Doing that at lower percents leads to some unexpected awesome strings.
The beginning of the match was good. The end you were trying something, but I don't know what. Always keep safe and don't try to switch up gameplay drastically in the middle of a match. You SHOULD switch up a lot in general, but don't start trying to do something that Ness shouldn't, which is standing grab or waste his second jump.
Always pummel at least twice when you grab someone (habit I've gotten into, which helps a ton)
When you dthrow, use awesome reaction timing to judge how they follow it up. With almost all responses except when the opponent double-jumps, you have a chance to follow up with Uair or Bair. If they DI forward from it, dash and put up shield, then OoS Uair (jump, let go, then C-stick up or up + A in a VERY short amount of time). If you want a Bair, you have to ditch the shield-dash and RAR. If you're lucky, you can also potentially regrab if the opponent is dumb, but then they DJ and you run after them with a jumped PKT and loop it back at yourself to run away.
