Next and last thing, let me introduce you to a new Luffy tech (let's call it the Disco Grab if nobody found it before me ) which rely on the aerial grab release from his neutral-b, here is what it looks like on a normal sized opponent (mario, basically to show it works on everyone):


So, basically what happen is:
1. Mario gets grabbed in the air and gets carried by Luffy's fall
2. The grab happening in the air, Mario is air-released as he's not touching the ground, carrying him a little bit upward compensating the fall
3. Mario is at perfect distance for a Luffy's up-b while still being in hitstun
4. Mario gets grabbed and thrown downward by up-b.
5. Maro iz ded cuz he sux

What is great about this tech is that it will up-b the opponent directly at a low height, making it impossible for almost everyone to comeback, and would still put them in a bad position.
It also can start while you're trying to comeback on the stage, which can surprise your opponent and be a great mix-up while also being fast (meaning hard/impossible to react to).
AND if the opponent dodges, well you'll grab the ledge anyway if used as a recover option.
(It can also be used as an offensive/edgeguard option but is more risky if you miss your opponent)
You can fastfall the neutral-b to carry your opponent lower but you won't be able to get the up-b afterwards (if you have double jump and down-b available you can recover after doing this), basically usefull on weak recoveries like Marth or DK who won't be able to gain enough height.

In a more specific way, you can see that Mario is still in "hitstun" after the grab release and while he's getting grabbed by up-b, he can't do anything against it, it is GUARANTEED.
BUT there's still something which can make it unguaranteed, and it is the momentum Luffy has while using his neutral-b, here I'll show what the failed version looks like:


You can see Luffy is too far on the right for up-b to connect due to the momentum I gave him while jumping off the edge. Else it should look like this:


So basically just be really aware of that momentum problem which can basically kill you and don't fastfall if you want to do the full combo, DI doesn't matter as much as I tried, so yeah, that's pretty much it for this tech, sorry if I had bad english ich bin french



Bonus: While fighting Sandbag to show this tech, something happened:
See how I hit that bomb with luffy's down-aerial? Why did that not hurt me? Why did I got stunned and got the "exploded" effect but didn't got any knockback nor damage?