Just hit escape to access the menu, then use left or right to select character, then hit enter to confirm your choice, then hit escape to leave the menu, and then enter a level and you'll have your chosen character
Oh, I figured it was something super simple that I was just thinking too hard to understand. I could've sworn there was a button you had to ground pound in order to swap characters, at least that's how it was back when Gura was added I think. Thanks for the help!
