At that point it would probably have been R-rated though.
When Detective Pikachu, the game, was first announced, a joke went viral on the internet that basically called for popular comic actor Danny DeVito to voice the eponymous character. While the final game did not have DeVito voicing him, Detective Pikachu still, amusingly enough, sounded suspiciously like him.
When the movie based on the game was announced, those hopes were renewed. The final movie has Ryan Reynolds, of Deadpool fame, voicing the character, which is almost as good, but as it turns out, very serious thought was in fact given to bringing Danny DeVito on board for the project.
According to Detective Pikachu producer Cale Boyter, “We definitely thought about it and how it might inform the spirit of it. Danny is incredible by the way. I am a huge fan of Danny DeVito.”
Speaking to Game Informer, he also talked about how they did screen tests with sound bites of different actors recorded over Pikachu, including, yes, DeVito.
“It was really very funny, so I couldn’t speak to all the reasons why it wasn’t Danny DeVito cast. I love Danny and some point maybe after the movie comes about, we can share those early tests. It’s absolutely hilarious.” He added that “the spirit of Danny DeVito… is still inside Pikachu”, which is probably the most motivationally inspirational thing I have heard all week.