* For a physical object that bounces: rebondissant (adjective)
* For a person who is energetic and lively: dynamique (adjective) or plein d'énergie (literally "full of energy")
Here are some examples:
* A bouncy ball: Un ballon rebondissant
* A bouncy dog: Un chien dynamique
* A bouncy child: Un enfant plein d'énergie