I don't think the Ruined Dragon is as out of place in the Mario universe as people say it is - it kinda reminds me of stuff like the Greedy in the Raggedy Ann movie; the Spirit Book in the Care Bears movie; or the Smooze in the My Little Pony 80s movie, a villain who's appearance and threat level is a little out of place in the overall cutesy world, but that adds to them as villain because of their out-of-place nature, and they add to the overall world by showing the darker magic you'd expect in any other fantasy universe.
However, I do think it should've been later into the game. Maybe as a post-game boss in Darker Side, or the second-to-last boss before Bowser.
However, I do think it should've been later into the game. Maybe as a post-game boss in Darker Side, or the second-to-last boss before Bowser.