My favorite Bowser battle is the last one from Super Mario 64, which I like to call Ultimate Koopa because that's the name of the music that plays during it. Anyhow Bowser really picked up in difficulty in this encounter from the previous two. Each time he got thrown off, he'd land back on the platform and cause shockwaves to expand in all directions. Eventually chunks of the stage would fall off until it looked like a star, and aiming Bowser for the mines became harder. It was a battle that I really enjoyed for its intensity for once, because I prefer casual encounters usually. But Ultimate Koopa did it right.