The freeze glitch is banned, but this is basically how you do it. Have Nana grab the opponent; if she f-throws or u-throws, forward+b with Popo at the exact moment she lets them go. They will be frozen in place.
The edge chaingrab--only an infinite, I think, on Bowser and Mewtwo--goes like this:
Grab with Popo near the edge.
Have Popo d-throw.
Have Nana grab right as they leave the ground so that she catches them. If she is near the edge, she will throw them off the level; for the chaingrab, this should be a forward throw.
Wait for her to f-throw, then grab them again with Popo.
Catch them with Nana.
Repeat.
The two are, interestingly enough, related because when Nana is near the edge, she always throws the opponent off it. This means you can control her AI so she will always f-throw. This means you always know that she is capable of setting up the glitch!
And that means that using Popo's d-throw near the edge, you can combo into the glitch. Neat.
Your most common options will be tech-chasing an opponent into a grab near the edge, doing an ordinary chaingrab across the level until you reach the edge.
If the opponent ledge hops an aerial right on top of you, you might get a shield grab there and be able to ledge-chaingrab them out of the shield grab.
You might also get it just by sliding into a jab or up-tilt while you happen to be near the edge.
I found a method of extending the grab so you get more damage out of it. Instead of having Popo do a dash grab to catch them, simply walk in front of Nana and grab in place. This makes you use less room while doing the chaingrab, which gives you more reps, which equals more damage, which increases the likelihood of zero to death. I have managed, using blizzards or f-tilts in between throws, to do edge chaingrabs from 0-death now, which is nice when the infinite is banned. It's also cool because you slowly, but surely, put the opponent closer to the edge which reduces the damage necessary to KO them!
It's nice that the IC's make DI pointless, huh?
