So basically it was three evolutionary stages of a Pokemon in one card. Not much is known what if any gameplay significance there was, but I know that it wasn't multiple different Pokemon like in the Tag Team cards. No, instead all three evolutionary stages were supposed to be the same individual who just can evolve from one stage to another.

The first two cards to be revealed was a Machop line and a Magnemite line. The images are an approximation of what I remember seeing. And yes, the fourth space is empty like that. You might noticed on the second card that instead of Magnezone, it's Probopass, which is from the wrong Pokemon evolution line. Apperantly, for some reason, they now allow Pokemon to evolve into Pokemon of a different line.

When this was reveal, the fanbase was very confused and baffled. Not because of the three in one evolution card(they were completely fine with that aspect apparently), but about Magneton being able to evolve to Probopass. There was a lot of complains online by fans about how Pokemon should not able to evolve to an unrelated Pokemon. However, there was also many fans who liked the concept and wiling to defend it. They thought this evolution was fun and interesting, liking it to what Digimon do.

I had a dream that Pokemon introduced a new type of card and it was quite controversial.