So yesterday I was reading a post on twitter that lead to an article talking about how Big Hero 6 will be included in Kingdom Hearts III. From what the article said, the story will take place after the events of the Big Hero 6 movie where the team is already created and Baymax is present. These two stories are a lot alike and will blend interestingly. They both have a strong theme of friendship, light and darkness, and teamwork that can easily be melded together. From what they have said so far, there is looking to be a Dark Beymax that Sora will have to help them fight. See the link here for the article. Also below is some concept art that has been released.