From Bulbapedia, the community-driven Pokémon encyclopedia.
Waterfall Colosseum is the third Colosseum in Pokémon Battle Revolution. The battle theme is Team Battles. The Colosseum leader is Colosseum Leader Marina. Like most other Colosseums, there are 7 battles in all.
Waterfall Colosseum is on the far side of the island from Pokétopia. It is a beautiful Colosseum surrounded by mountains, trees, the sea, and waterfalls.
The battle theme, Team Battle makes you pick five out of six of your party members, and individually faces them off in elimination one-on-one fights against the opponent's 5 Pokémon. You are not allowed to switch Pokémon; knocking out the opponents Pokémon gets you a star and an O appears next to your Pokémon. If the opponent's Pokémon beats you, they get a star and an O, and your Pokémon gets an X. Then the second Pokémon you picked goes up against the opponents second Pokémon. The minimum amount of battles is 3; the first Trainer to get 3 victories/stars (Out of five possible battles) wins.
After you beat the game, you may select the level 50 All rule. You use two Pokémon for each round in a double battle. The maximum amount of battles and the minimum amount of battles are both 3. Other rules remain the same.
Beating Waterfall Colosseum for the first time in Level 30 Open mode gets you Pikachu facepaint, a custom battle pass with Waterfall Colosseum in the background, and 350 Poké Coupons. It also unlocks two new Rental Passes at Gateway Colosseum, as well as the next two Colosseums, Neon Colosseum and Crystal Colosseum. Beating Waterfall Colosseum for the first time in Level 50 All mode unlocks 23 pieces of gear in the shop. Also, when the player beats Marina for the first time in Level 50 All mode, they obtain her Kyogre outfit. There is a small chance of Marina wearing a shiny outfit when you battle her in Level 50 All mode. If the player beats her while she is wearing a shiny Kyogre outfit, they will obtain a shiny Kyogre outfit of their own.
The default mode of battle here is Single Battle. An option to change this to Double Battle is made available after beating Rank 1 for the first time.
The Pokemon and Trainers are not set, except during the first time you battle there, at Rank 1 Level 30 Open, and the first time you battle using the Level 50 All mode, Rank 1 Level 50 All. The Trainers, and the Pokemon they have, go as the following during Level 30 Open, Rank 1: