User blog comment:Travzilla22/My Second episode wish/@comment-961279-20121115072440

Which Avengers? The ones from England headed up by John Steed? Or the ones from the Marvel comics?

If it's the Marvel comics, then Phineas and Ferb is already going ahead with a crossover with them. Since Disney owns Marvel, a second crossover between a Disney property and a Fox property isn't as likely.