That is one of the legendary Pokemon Snap prize cards given to the winning entrants in 1999’s Pokemon Snap contest using the N64 video game. There are 10 of them, and they are limited to 20 copes each. Insanely rare, and insanely expensive, and have been for a long time. Azul is among the finest Gyarados collectors in the world and has been searching for this for millennia. Another member here on the forum has one, and was actually his competition in getting that one. Here’s a forum article on it from some years ago:
www.elitefourum.com/t/pokemon-snap-cards/14489/1
As for my grail from this set would be Koffing. My overall grail would be a Kang of course, now that I have my Porygon! 