Well. This was very interesting.
First, I checked the light test.
No light passes through with a normal wattage bulb. That's good.
With a bright light, some passes through, looking mottled.
I compared this with a non-holo shadowless card and it is similar to that. That's good.
Using a magnifying glass, I check the edges for the black sandwiched layer.
For those unfamiliar, Pokemon cards are made from three layers. Two white layers sandwich a black layer.
That black layer blocks most light from passing through the card.
The card does have a black layer. That's good.
At this point, things were looking very good. I wasn't expecting it to pass those tests.
Next, I start looking at the printing.
The printing pattern matches well with the Magneton card that I have. Ink dots are laid down in a correct pattern. That's good.
I look at the printing on the energy symbols. This is not so good. The black shadowing on the Energy symbols is much darker on the test card.
Muddier. This is a concern.
The finish on the card is matte. Compared to a non-holo shadowless card, which has a semi-gloss finish.
However, when compared to a holo card, that is also matte. So, all in all, this is not a concern.
The final thing that I looked at was the border. I noticed that the border is a different color that either of the shadowless cards I am using as reference.
It is not a slight variation. It is a different yellow. I have looked through many, many cards of the era, and have found absolutely none that use this yellow color for the border. It is so wrong, that I find it to be a sticking point.
Combining the muddy printing on the Energy symbols with this wrong border color, I find that I cannot verify this card to be real.
It may very well be a real Pokemon card. The card stock seems to be correct.
However, that border just doesn't match up with what it is supposed to be, and that keeps me from saying that this is a real Base Set shadowless error Magneton.