The joke is that each of these beasts is the creature on the cover of the games of their respective colors.
Pokemon (Fire) Red, White, Black, and... Yellow.
The original Red had Charizard, at least, but Pikachu was on the cover of Pokemon Yellow, and there's never been a remake for Yellow as with Red and (not-released-in-America) Green.
The joke is that each of these beasts is the creature on the cover of the games of their respective colors.
Pokemon (Fire) Red, White, Black, and... Yellow.
The original Red had Charizard, at least, but Pikachu was on the cover of Pokemon Yellow, and there's never been a remake for Yellow as with Red and (not-released-in-America) Green.
Yeah, but White and Black had Reshiram and Zekrom on their covers.
The joke is that each of these beasts is the creature on the cover of the games of their respective colors.
Pokemon (Fire) Red, White, Black, and... Yellow.
The original Red had Charizard, at least, but Pikachu was on the cover of Pokemon Yellow, and there's never been a remake for Yellow as with Red and (not-released-in-America) Green.
No. Groudon is there for Pokemon Ruby version (how'd you miss that joke?). Kyurem was on the covers of Pokemon Black 2 and White 2. Darkrai has only ever been on the cover of Pokemon Ranger: Shadows of Almia (a game not in the main series). And Pikachu was on the cover of Yellow Version. That does not mean the joke is about the games covers though. The joke is, more likely, about what Pokemon lunarisaileron thought fitted with the charactes based on the info we had on them from the trailers at the time. Or they were the Pokemon of the matching colour that immediately came to their mind while working on the piece. For the best answer though, it'd be best to ask them on their deviantart account.