ok so I've been on a MAJOR Power Rangers kick lately and I found this website that gave all the information on Power Rangers as well as other shows like Beetleborgs and this other show called Kamen Rider Ryuki. I was looking through the subcategory "Contract Beasts" and found these black dragons with gold trim were fairly close in design with a shiny Rayquaza.
now, I don't know if anybody legitimately ripped off the other, because KRR was running the same time that Ruby and Sapphire came out in Japan. maybe it was pure coincidence? i doubt it, because they all look FAR too similar for this to be done by chance.
as it would appear, the Kamen Rider Ryuki show was released in the early 2002 and ruby and sapphire were released in late 2002 in japan. They were more than likely going through the design stages at the same time. The dragon may instead be a fictional or historical figment that the two of them based it's design after. The Kamen rider is all in black, which is more than likely the theme for the dragon. Where as the black for Pokemon was probably thought to be a cool alteration. I don't think either of the two had copied the other. When they designed Rayquaza, Groudon, and Kyogre, they all had Mesoamerican themes to them. As for the Kamen rider, that show dates back to 1971, and is more than likely trying to appeal to the youth. Either way, I feel that it was just a coincidence. Good eye though.
I'd be far more inclined to call shenanigans if these weren't recolors we're talking about. Dragblacker is a recolor of Dragredder, and this is the Shiny version of Rayquaza. If you were to look at their original forms and they were the same, I'd be more inclined to say something of the sort went on. But if you look at them, Dragredder and regular Rayquaza have very little in common.
Good ole Dragblacker. The coloring is pure a a fluke. He's the contract beast for Kamen Rider Ryuga, Ryuki's Mirror World clone. In turn Ryuga's and black recolor or Ryuki's Red colors. Same goes for his Mirror Monster, a black recolor of Ryuki's Dragreder, seen here. [link]
I think it's more of a coincidence thing than a "who ripped off whom" situation. I mean dragons have been around for ages, so you can only do so much with them design-wise before they start looking similar to one another, right?
It's actually not so similar if you watch the show. Genocider (top left) is made up of 3 different beasts (none of which is primarily black), and is mainly silver, pink and purple. The part on it where the designs are so similar is actually a giant purple snake.