Many years ago there was at least one YouTube video in which someone compared tracks from Pokémon games to music from elsewhere.
The only comparison from it that I can remember made note of an overworld track from Pokémon Diamond/Pearl/Platinum, I think the one that was used in Route 215 and in some others. The video pointed out how that track sounded similar to 21 Guns by Green Day.
And of course, much more recently some people noticed that the battle theme for the Treasures of Ruin in Pokémon Scarlet/Violet sounds similar to Tunak Tunak Tun.
I can't seem to find the actual news story now, but I swear there was some lawsuit circa 2011-2012 about some talent show winner's (maybe Britain or America's Got Talent?) lead song "too closely" resembling "Under the Bridge" by Red Hot Chili Peppers.
The song "Snowbird" (best known version by Anne Murray) and Songman by Cashman & West while having slight differences in a few notes and Songman is slower than Snowbird, I think the main melodies are quite similar.
I don't know if this counts because I heard that both of these songs borrow from a 18th century French opera. They were just adapted into folk songs in their region.
