My husband and I went to see Deadpool yesterday along with our 19, 16 AND 13 year old offspring. Was I a bit concerned that it may be too much for the 13 year old? Most definitely. Do I regret taking her? Not. One. Bit.
I know my 13 year old. I know her level of maturity. I know what she has and has not been exposed to over the years regarding language and what some may be considered inappropriate behavior (her favorite band is Falling In Reverse, and if you don't know what I mean by that then read some of their lyrics). I also know that she is a straight A student, top of her class, LOVES Marvel (as well as Anime and other fandom's) and that she could handle it. On top of that, I know what 8th grade boys talk about, reference and discuss on a regular basis, and that she knows a lot more than I am comfortable with because of it.
I feel that for anyone under the age of 16, 17....the thing to consider is the individual child. I would never let my daughter watch American Horror Story because it focuses SO much on sex and adult content and honestly that is what people watch it for. However, we, including my daughter, did not go to see Deadpool for that reason. We went to see Deadpool for the comedy, the action scenes and the overall comic universe aspect of the film. So, she covered her eyes during the sex scenes towards the beginning (many of which you can see just as much of watching cable of HBO shows these days) and as for the boobs and otherwise in the strip club, well, she is a girl - it's not like this is not something she see's each and every day and will for the rest of her life (at least, I hope so).
I know my kids. I know what they can handle. I know that she is fully capable of not allowing a movie, nor a song, nor a television show influence her in a negative way. For younger children, I fully agree that they should not see the movie. But as for me and my 13 year old, considering how awesome she is thus far, I think I have made some pretty good parenting decisions up to now, and I doubt that this "bad" one will make that big of a difference.
By the way, we all enjoyed the movie, will probably see it again, and are already looking forward to the sequel.