Seriously everyone should have figured this tech out by now. Run to the edge when they grab it, and hold shield forward on control stick and back on the cstick. If they hit your shield then you can buffer aerial and then get stage spiked, or spiked or u can even footstool. If they dont do a thing then u roll backwards.
From what I'm getting from this video, ISSDI inputs must be inputted during the actual shield lag, as in holding towards the ledge the entire time does nothing when MK actually decides to Uair your shield. In order to fall off the stage, you must slam the control stick towards or down-towards the ledge in order to fall off the stage. The issue here is that, shield lag from a Uair lasts 6 frames, and reacting to it in 7 frames(1 frame of startup on Uair) is a crazy feat to expect, so we can only guess when MK's gonna pull out that Uair(as a tradeoff, however, MK will not have any invincibility to work with when he inputs his second Uair, because he'll be using it to change up the timing of his ledge moves).
The problem here is that, if you misjudge when MK is going to throw out his first Uair, you're going to end up inputting a roll towards the ledge, or a spotdodge, which leaves you wide open for some punishment on MK's end, because Uair doesn't have all that much endlag, as we all know...
There's also the case that MK decides to use, say, Fair or Nado, for example, because you'll ISSDI right off the stage and into his attack. Not fun.
If we could just hold our control stick towards the ledge, and end up falling off the stage when our shield got hit while holding the control stick like that, then yeah, MK's planking wouldn't be broken in the slightest, but we can't react to it at all...
I thought I should just point it out.
But I still think, as obvious as it may seem, that both communities are different, play the game differently, and it doesn't have change especially when it's been mentioned that the cause of Japan's win over the U.S might not have been only and simply the differences in our rulesets.
Yeah, I feel that there other factors that we can look into aside from ruleset, considering I'm pro-ban and all that, but... I can't be sure if my reasoning is right or not at this point, either. It could've been their ruleset, or it could've been their culture, great internet, high pop. density, etc. that caused their dominance over us at Apex.
It all needs to be looked into, but I'm kinda hesitant on taking a stance in this particular argument, hence why I've merely been asking questions all over the place when Japan comes up as the topic.