Is Shakamon Gokuwmon's mega form

No, Shakamon is not Gokuwmon's mega form. Gokuwmon is a Digimon that belongs to the Digimon franchise, and its mega form is actually called Gokuwmon's ultimate evolution, which is known as Gokuwmon's mega evolution. In the Digimon series, each Digimon typically has a specific evolution line that includes various forms, including rookie, champion, ultimate, and mega.