Well, as much as I like Big Hero 6 and especially Baymax. We don't seem to see a lot of crossover works with Big Hero 6. If one of my characters had a chance to match their skills with Baymax I would gladly take the opportunity.
Plus, given the many technology based villains in Marvel and Pixar alike. There is a possibility of a bad guy trying to hack Baymax's system so someone has to be able to stop him.