I'm sorry define " A cultural phenomenon" for me.
Something that is so popular that it transcends the traditional bounds of its genre/subject/industry type and becomes tied to the broader popular culture of its time.
I think there is some confusion here as to something being popular, but popular or successful alone doesn't mean it's a "cultural phenomenon".
The Avengers is a popular/successful movie, but I wouldn't say it's a "cultural phenomenon". Titanic (1997) was a cultural phenomenon.
The Macarena is a cultural phenomenon. Michael Jackson's Thriller is a cultural phenomenon. The Beatles are a cultural phenomenon. Pokemon is one for sure, it's actually now twice phenmeonon, which is exceptionally rare.