Mew2King
King of the Mews
found this trick out months ago (actually, MikeHaze showed me and he said DEHF showed him), but for those who don't know...
after MK does up B he can press down B at the same time (after his shuttle loop animation/lag ends) and he will fast-fall and land with no lag. This works because before he goes into free fall mode, (which happens after that tumble-flip thing) if he lands in that time period before the flip animation completely finishes then he will have no lag upon landing. This isn't just needed on the ground; you can even jump in the air and shuttle loop right away and still cancel with no lag, as long as you do it fast enough (not hard at all).
after MK does up B he can press down B at the same time (after his shuttle loop animation/lag ends) and he will fast-fall and land with no lag. This works because before he goes into free fall mode, (which happens after that tumble-flip thing) if he lands in that time period before the flip animation completely finishes then he will have no lag upon landing. This isn't just needed on the ground; you can even jump in the air and shuttle loop right away and still cancel with no lag, as long as you do it fast enough (not hard at all).