In an interview with IGN T.J Miller claims Deadpool 2 will be equally as funny as the first thanks to Ryan Reynolds of course.
“The good thing about that film is that Ryan is really f*#king funny,” said Miller. “Really fast, really smart, and knows that character. That character is kind of him. It’s the defining role in his career, it really is, and he really does like Wham, and he’s like Deadpool kind of, and he’s sarcastic. it’s going to be very, very funny, we know that. The question is do the fans feel like it’s an appropriate follow-up and I think [writers] Rhett [Reese] and Paul [Wernick] and Ryan are like so passionate about making it better that it probably will be.”
See the full segment here- http://uk.ign.com/articles/2017/05/25/tj-miller-on-why-deadpool-2-will-be-just-as-funny-as-the-original