Project X Zone 2 is a fun game that was a mashup of many other franchises into one singular experience. It seems there was interest in having Bayonetta included in the title. Sadly it seems Hideki Kamiya turned down the opportunity. In a series of tweets, Kamiya explained that there was an offer on the table to have Bayonetta in the game but turned it down, and now regrets it.
It would have been interesting to see Bayonetta appear in more franchises, although for now you may have to settle for Smash Brothers for the Wii U. Maybe when Project X Zone 3 comes around, she may make an appearance.