From the Super Mario Wiki
Plok is the protagonist of a video game of the same name. He is a big-eyed creature with the special ability to throw his arms and legs away. Plok only appeared once in the Mario franchise, on the planet Hösndösn in the Club Nintendo comic "Super Mario: Verloren in der Zeit". Though actually living on the island Akrillic, Plok takes part in the "intergalactical Olympics" of Hösndösn. He seems to be very sportive as he and Mario are the last two competitors in the games; it is also mentioned that they are breaking several records. Nothing is known about his character though, since he does not speak in the comic.