>>56825718I doubt censoring had anything to do with it. They censored episodes and lines in the show, but usually just the very overtly transgender stuff, ogling minors, and guns. They were fine with scenes of people running around in underwear/pajamas, Brock hitting on girls all the time, and the weird crossdressing stuff Team Rocket does all the time. The line from the Japanese opening would probably have been seen as harmless fun, along with the scream that plays at the end of it.
IMO, the Japanese opening is just a nightmare to try and localize 1:1, which is part of why they just wholesale created a brand new one. They were never going to just play it in Japanese with subs; that type of thing would never have worked in the US market back then, and not even shows on Toonami did that often back then. The Japanese Pokemon opening is all very fast rhyming and wordplay. In Japanese, it comes across as being really well-written and catchy, but would probably not work nearly as well in English. Additionally, it's about 30 seconds longer, which matters a ton to networks. That's an extra 30 seconds they could otherwise play ads. So instead, they just had an original song written and reused some of the opening footage to make a minute-long opening.
Here's an example of someone trying to cover it in English. It's actually a pretty good attempt, but you can see that the rhyming only really occurs on the ends of phrases, if at all, rendering the overall impression of the song less effective.
https://www.youtube.com/watch?v=4-C5I8EKrag 
