http://www.youtube.com/watch?v=23UyrHXK36A
Let me do some explaining here:
I play against some of the best Luigi players in the midwest in Sandwhich and TheMann. What I have noticed when I play against Luigi that his game involves a lot of constant pressure and comboing. Also, Luigi's key feature is his FAST aerials and his relatively low lag. However, Luigi does not really approach on the ground, he approaches in the air because of his aerials. His ground game is not super good, but his down B can get him in and out quickly for some quick pokes.
All of this together gives Dedede MANY opportunities for shield grabs. As a Luigi player, you need to be EXTREMELY careful as to not get shield grabbed, because this will start the infinite. However, you also have to watch out because if you're just floating around in front of him, you will likely be in up tilt range. That's what should be going on in a King Dedede main's head. The luigi player really only has two options and that is throw fireballs from midrange or approach with quick aerials. Both of which can quickly change into King Dedede's favor.
Key information on the infinite:
Ankoku and I originally did a lot of research on this infinite and he came to the conclusion that the "stale moves list" only has 9 moves in it maximum. Here's how that applies to King Dedede:
With Mario, Luigi, and Samus for some reason after 5 consecutive down throws, the move stales and King Dedede is not able to regrab them. With Samus and Mario, however, they can be regular chain grabbed afterwards, which usually leads to an easy zero to 70% combo in addition to an edge guarding attempt. Luigi players are lucky in the sense that Luigi slides all over the place and prevents King Dedede from chain grabbing him regularly so he can't follow up. This is where the stale moves list comes in...
If I do 5 consecutive throws, you break out between the 5th and the 6th throw. However, a grab attack (Dedede's head butt) also counts as a move in the stale move list. Look at these possible stale move lists:
1. down throw - down throw - down throw - down throw - down throw
You will break out automatically after the 5th throw
2. down throw - punch - down throw - punch - down throw - punch - down throw - punch - down throw
Here's 9 moves in the stale move list alternating a punch and a down throw. Since the next move would be a punch the next stale move list would read:
punch - down throw - punch - down throw - punch - down throw - punch - down throw - punch
Since there are NEVER more than 5 down throws in the stale move list if you add in a punch between each throw, the move will never stale and it is an infinite.
As far as being able to get out at early percents goes, in smash you are naturally more and more unable to break out of throws the higher your percent is at. So, at 0% you can break out RIGHT after a punch where by 50% a punch is nearly guaranteed if the King Dedede player buffers in the punch after the grab. Which means they can infinite you starting at around 50%. That's why the infinite is so good and so hard to break out of.
I hope that helps and please let me know if you have any more questions.
