The color of a few pictures will be strange, because it downloads as a series of PNG format pictures, and then these pictures have no palette data (https://en.wikipedia.org/wiki/Portable_Network_Graphics#Critical_chunks ), resulting in the lack of the corresponding palette data when converting to GIF and then it becomes like this. But I think it doesn't have a serious affect, so I don't correct it.
I don't play this game so I can't answer you certainly. But I guess it MAY be a collaboration between these games, because the number of files in 1-50 are N rank cards, 51-150 are R rank cards, 151-250 are SR rank cards, 251-610 and 1001- are SSR rank cards, no cards in 611-1000. I think 611-1000 will be used in future, and 1001- may be the collaboration cards.