Maybe Takamaru, since Sakurai planned for him to be playable early in Smash 4's development, since he's apparently very popular in Japan, but realized that he'd have no international appeal due to being from game only released in Japan and heavily based on Japanese history. Hence, he's just an assist trophy.
I'd say they might've already gotten their Ridley: Inkling. Splatoon is pretty popular in the West, but you can't understate how popular it is in Japan. Splatoon 2 was the first game to sell over 2 million units in Japan for a decade, and did that well before Breath of the Wild could sell just 1 million over there. It's one of the most popular games/franchises in a long time. So I imagine that, while the reveal trailer for the new Smash back in March was huge for us because "Oh wow, another Smash game already!" it was even crazier in Japan, because it was that, but a lot more of "SPLATOON IN SMASH!"
So in a way, we both got our Ridley already. Makes sense why they'd both be the first ones to be revealed.