You can get this on Power of Love, the Pink Lanterns stage, with no need for Free Play. In the first act of the stage, there's a few flowers you can use as platforms that make you bounce, bounce on them 50 times and the achievement unlocks.
You can also get this on the Hall of Doom, located on the Hall of Justice Hubworld, but you need to complete a few missions there to get access to the mushrooms that make you bounce.