I know a lot of people here started with Brawl IC's and moved onto PM. I feel like I haven't seen a lot of Melee tricks (which are now optimal with the lack of wobbling) implemented into gameplay.
Spacies are my absolute favorite matchups in PM because of all the stylish grab tricks you can do on them. A decently well known way to style against spacies in Melee is grab>Nana charge fsmash>dthrow (they're di'ing in because they don't want to die)>release Nana fsmash & grab with Popo at the same time. This makes the spacie eat an fsmash and stay in Popo's clutches.
Here's a gif of me doing it to a Falco:
http://gfycat.com/DesertedDiligentAlleycat
It looks so nasty. I did this a couple times to IPK's Fox in friendlies and the others around me were freaking out. While it's only style in Melee, it's actually optimal in PM. If they realize, they might start di'ing out during dthrow so they can't be regrabbed by Popo.
Gif:
http://gfycat.com/CompetentEmbarrassedGermanwirehairedpointer
But this allows earlier fsmash kills (like 60% early). Yay for DI mixups!
Another grab trick (mostly still for style in pm though) is bthrow>nana wavedash back regrab. If you're near the edge of a stage but facing away, this could get you in a handoff situation. You've gotta be quick though. Drunk Sloth was the first to popularize this. He even took a set off of porkchops ending it off with this.
Gif:
http://gfycat.com/TallIllEnglishpointer
Something that is widely used in Melee that only started working in 3.6 (I guess because grab release, I could never get it to work in 3.5) is instead of Dthrow>Fsmash, use Uthrow>Fsmash. This sends them in the opposite direction. So now you have a DI mixup on every character. This is probably known by most people here, but I've never seen any PM IC's use it.
One last thing. Be careful of dthrow>usmashing G&W when facing to the right:
https://www.youtube.com/watch?v=2iauEHIaGGY
(I was going to say something regarding why dthrow>dair feels so much worse in PM, but it really doesn't matter anymore since the game is completed. Now we get to practice with what we have which makes me soooo happy.)