Club Battle is a 16-competitor tournament consisting of four rounds, and entrants are allowed three Pokémon each. All rounds consisted of 1 on 1 battles against randomly matched up Trainers by a computer.
This is the first major battle tournament where Team Rocket aren't selling merchandise or snacks (due to them being busy preparing for their operations in Nimbasa City).
The Pokémon Ash entered for the tournament were all used in Ash's then-upcoming Gym battle against Elesa in Dazzling the Nimbasa Gym!. Indeed, Ash said he would use the tournament as a warm-up for his Gym battle. However, he was not planning to use Snivy and Pikachu in his battle with Elesa.
On Pokémon.com, this tournament is also referred to as the Nimbasa Town Pokémon Battle Tournament, Pokémon Club Battle Tournament, Nimbasa Pokémon Battle Tournament, and the Nimbasa Pokémon Club Battle.