I've been working on getting down PKT2 as hard as I can since 2.5's release. As a Ness player, hard main on Ness for P:M, I'd have to say PKT2 is your most valuable survival skill and definitely the thing to learn if you're going to main Ness. It's comprable to Fox's shine or Pikachu's tailspike. If you don't/can't learn it, don't plan on anybody taking you seriously.
Now onto what I came here to talk about. PKT2 is a serious pain to get used to, especially after a year of playing wtih it in 2.1. It feels very off if you try to use 2.1 timing, which is why more often than not I have not been able to sweetspot anything since the release of 2.5.
I've been sick the last few days, so the soonest I'll be able to really get down to business is tomorrow, the 5th.
PK Thunder now gives you some static protection, much like Snake's Up-B. But, sadly, it isn't that strong. It's nothing compared to a half-decently timed bair from most characters. I'd think it's safe to say, never try to use/abuse/depend on these protections.
Speaking of half-decently timed bairs, just avoid them at all cost. Ness should never be PK thundering right off the edge when his opponent is right there (or on stage period). I've made this mistake so many damn times, and getting lucky. I remember thinking more than a dozen times in one night "I shouldn't be alive".
If you can go high before using PK Thunder, that's great. PKT2 can now act even MORE quickly after landing at the right angle to help keep Ness safe. It's been given even more distance than before, so it's safe to say, if you're opponent can't jump high, it's pretty safe to space this correctly and Thunder down. Do your absolutely freekin darndest to gain back middle ground. Otherwise, you're screwed even if you land.
Playing against spacies is the worst. It still feels like Ness is seriously limited when dealing with these, even with his slight speed boost. Angled fsmashes, uthrow chains, and yoyo combos really help, but they're very predictable in my book, and all 3 spacies can get out of these rather well and pretty much break any combo with a good shine.
Especially against spacies (in case is wasn't common knowledge, which it should be) get used to being extra damn patient, and hold that shield a little longer when being shffled against. 99% of the time, they WILL shffl into Shine with only 2 frames between active hit boxes. Shield->jump->nair and Shield->grab will never work against these.
Thankfully, like peach, nair can be useful for getting out of many offensive patterns from a lot of characters. Too bad Ness's hitboxes don't reach that far. Not by a mile.
Yeah, I'm definitely daydreaming, thinking I know what I'm talking about. But if there's any hope for Ness players, I think we can all appreciate input from any players who have taken any tournament (that has been advertised and posted on smashboards).