Shohei Ohtani is doing something that has never been done before. A lot of people compare him to Babe Ruth because of his dominance as a pitcher and a hitter, but they fail to understand that Ruth spent the early part of his career primarily as a pitcher and didn't dominate on the offensive end until after he essentially stopped pitching almost entirely. Ohtani is doing both at the same time!
What we are seeing from Ohtani is hard to put into words. To me it's him, full stop. When it comes to boxers it's common for a boxer to dominate not just in one but in multiple weight classes, so I don't even see how you can compare their accomplishments.