Thread:Trigger009/@comment-5607612-20170823211017/@comment-24922135-20170823213057

Your source confirms that Decagon Vreedle exists with the Omnitrix. It does not confirm that he was ever unlocked.

tbqh we don't have any actual confirmation that Shellhead, Snakepit, and Sandbox are in the Omnitrix. For all we know those aliens are from the Andromeda Galaxy and therefore not present in that version of the Omnitrix (at least not yet).