In our history, the Fab Four started out as a typical pop rock and roll band, but their musical horizons grew by leaps and bounds to a degree considered revolutionary (excuse the pun) even today. What this does not mean, however, is that the Beatles' material ended up a majority of rather harder material - even if Paul McCartney wrote Helter Skelter, he's still considered the Beatle who wrote "silly love songs" and was generally dismissed by John Lennon to be such. And George Harrison, even if he was a good musician, doesn't have a lot of famous roaring solos to his name.
So, my challenge is: with a POD no earlier than 1962, make the Beatles' body of work harder on the Mohs Scale of Rock and Metal Hardness, overall; with compositions like Helter Skelter being more numerous.