I had heard that he had issues as Mark Antony, but I do consider Stanley Kowalski to be very different from Vito Corleone. I didn’t see him as Fletcher Christian. Now that you mention it, he was badly miscast in “Guys and Dolls” as well.
Brando ONLY "played to type", which isn't really all that much of a stretch, re acting. From the black leather jacket leader of a motorcycle gang, to his role in ON THE WATERFRONT, to a brutal, nasty man screaming at his wife in "A STREETCAR NAMED DESIRE", to a Mafia "DON" are all roles more or less in the same genre.
Brando as Napoleon,Mark Anthony,a Japanese conman of sorts? All utter disasters!
Now compare him to someone like Sir Laurence Olivier, John Gielgud, Robert Montgomery, William Powell, or even Clark Gable....NO COMPARISON; all of those actors could and DID play many different roles and were believable in every single one of them!