So, as mentioned in the video linked above, the way holofoil works is that the nonholo parts of the cards are blocked out by an opaque white blocking layer.
So underneath the body of hitmonchan will be a solid white, the background normally would not receive that so the holo shows through the color ink. In this card, the blocking of hitmonchan seems fine.
The image below suggests that white ink is appearing where it normally would not, which is why this part of the card is nonholo
The odd characteristic is that there seems to be the shape of the Ninetales blocked out, as pointed out:
The error below happened because they used the wrong blocking (ie Kyogre mask used on Groudon and vice vera). It’s a related error but not the same thing. The difference being the Hitmonchan has both Hitmonchan and Ninetales masks simultaneously.
The confusing part is that this is actually the inverted Ninetales layer, ie. the background has the white ink instead of the Ninetales.
The way that the printing machine works is that water and ink (pink roller) are applied to a printing plate. The surface of the plate is designed such that the parts that receive no ink attract water and the parts that should have ink attract oil (oil and water don’t mix), The ink on the printing plate is then put onto a rubber blanket and then rolled onto the paper.
An issue called ghosting can happen when you have areas of high ink concentration right next to areas of low ink concentration. The inconsistent application can cause certain parts of the sheet to be relatively starved of ink example: Explain this to me - #14 by pfm
Ghosting is one way you can have one part of the sheet affect another.
Some kind of mechanical ghosting may be the explanation here… but the weird thing is that the Ninetales layer is inverted.
In contrast to this Chansey, which may be an example of “blanket memory” (a type of ghosting). This is when some of the ink is not released from the blanket and ends up being applied on a subsequent sheet.
I don’t know if I fully have the ability to explain it. But some phenomenon is likely holding the ink on the blanket in the shape of the Ninetales, and redepositing on a subsequent sheet. This explains why both the Hitmonchan ink shape is proper and why you have traces of the Ninetales.
Consider the sheet below.
(note: the sheets go though the rollers left-to-right, not top-to-bottom)
Hope that’s useful
