The signed cards are, in my opinion, evident fakes made with an autopen. If you don’t know what an autopen is, you can find a lot of information about autopen generated autographs on google and on youtube. It’s a well known phenomenon among sport or politic memorabilia collectors, so it’s not something invented by this specific seller.
He’s been quite crafty and produced three different patterns for his signatures, cause one of the issues with autopen stuff is that they’re all exactly the same.
However, they all can be tracked back to some of the first results you can find on google images when you search “Ken Sugimori signature/autograph”, I found them with 2 minutes of browsing, they all share a white clean background, which obviously makes the work pretty easy.
Me and a friend of mine tried to quickly make some photoshop comparisons to make it easier to see, but your eyes are the best proof, you can definitely see that they are perfectly superimposable.
Venusaur and Blaine’s Charizard share the same pattern of this Nintendo DS, for example. I’ve seen another card with the exact same signature as the Blastoise, a Dark Charizard to be precise. I don’t remember where I’ve seen it
Charizard is trickier, cause he repositioned the kanji and the western signatures a bit, so they don’t perfectly line up with the source material. They’re just the same as the original, tho, they can be overlapped quite easily as you can see.
Venusaur comes from this piece, I had no time to make a photoshopped comparison, but you can see it yourself without any problem
It’s quite sad that psa was tricked by this kind of thing, but I can see why it happened, they’re really well done. I don’t want to imagine how many Arita’s signatures will be faked, cause he recently produced thousands of autographs, so tracking the specific source of the autopen ones will be pretty much impossible.
Hope it can help!