Another day, another time I'm forced to go out of my way to stop the spread of misinformation.
I'm just going to repost what I wrote on discord, in response to this which is likely to make the rounds among the serial complainers (note I'm not talking about the person who took this, I'm talking about the ones which are filled with joy at the prospect of spreading misinformation about Mewtwo).
This rest hit Mewtwos tail, which certainly gives the impression that his entire tail is a hurtbox, but theres something else going on here.
I tested it pretty easily, it appears that during the rising animation of mewtwos jump, his tail tip briefly enters the z axis, but the rest of his tail actually doesn't
In the first picture there, the tip of the tail is hittable, but not the main body. A few frames later, or during the double jump, almost his entire tail actually enters the z axis as is unhittable. It absolutely seems like the issue of it passing into the z axis is a bug. There's no reason by the mid section of the tail is out of plane, but the tip is, and then the tip moves into it a few frames later where it stays.
Now of course, it doesn't help much if the tail tip is hittable but the mid section is not, you're going to get hit anyway. The important question is, how often are you going to be in a situation where the tip of his tail is going to be in the enemies range, while you jump away from them? the answer is almost never, so its basically not a problem.
The takeaway is this is a bug. Yes it is an obvious flaw, but it is a flaw that is almost never going to affect actual gameplay because it is so rare it will ever happen. Its like Mewtwo bonking in smash 4 on the stage. As long as you didnt use upb at a 0/180 degree angle, you would literally never run into this problem. A flaw, but inconsequential.
vs 
