It sure doesn't LOOK legendary.
This definitely looks like it evolves. Water starter, maybe? Or are all those released at the same time? The three silhouettes below, maybe?
"Prince of the Sea" sounds like a title reserved for Kyogre instead of this blue half-blob thing. Of course, it's entirely possible that this cute little bugger is indeed the prince of some sea.
It does look like a Water-type, especially since the surrounding image is an ocean. The small picture of Manafi in the group of three on the left reminds me of Mantine. Maybe this thing can fly?
The far left silhouette at first reminds me of Manafi. And Dustox. It certainly does look like some type of bug.
The center picture looks like a Wurmple standing on its back feet.
Other than that, I don't have a clue. Eeveelution? Nah. I really don't think they'll give Eevee any more evolutions.
The last one looks like a bird of some sort. I can see what looks like a large, curved beak on the left side, maybe a ring of feathers around the neck area, and some bulb thing on its tail. As for the scythe-looking thing... a raised wing, perhaps?