Shiranui pulled out his Pokédex.  "[i]Spoink, the Bounce Pokémon.  Spoink bounces around on its tail.  The shock of its bouncing makes its heart pump.  As a result, this Pokémon cannot afford to stop bouncing—if it stops, its heart will stop.[/i]"
"We better find its missing pearl before we take on the gym," Shiranui suggested, "Spoink, just keep bouncing.  We'll help get your pearl back."