Reverse Ball is an attack used once by PallaPalla in the manga and anime. It swapped ages between targets.
It was first used at the end of Act 39 when the Amazoness Quartet were watching Sailor Moon and Sailor Chibi Moon from their mirror. Wondering what the senshi's dreams could be, they were able to read their minds and found out that Usagi wished she was more of an adult and Chibiusa wished the opposite. But, as they had been complaining about the disadvantages of being an adult and being a kid, respectively; PallaPalla cast the spell as the senshi detransform using her Amazon Stone and once back in their civilian identities, their ages had already been swapped. The spell was broken in Act 40, when Usagi and Chibiusa used Moon Crisis, Make Up!.
Aside of the change in bodies, the attack didn't have any other side-effect.
It was used in episode 158 when Sailor Moon and Sailor Chibi Moon stopped an attempt of the amazon to collect Dream Mirrors. In the middle of the fight, however, the two senshi started arguing about wishing of become an adult and wishing of become a kid again. PallaPalla was listening to all of that and decided to make their dreams came true: She joined hands, then opened them (but keeping her wrists together), and then rotated her two hands, effectively swapping Usagi and Chibiusa's ages.
The curse was broken in that same episode with Pegasus' aid.
Under the spell's effect, Sailor Chibi Moon couldn't perform Twinkle Yell.