Waterfall Colosseum

The Waterfall Colosseum uses an interesting style of battling, where rather than being able to switch between your Pokemon at will in a battle, each battle round consists of 5 Pokemon from each Trainer's team being faced against one another, in a one-on-one-style battle. You can't switch your Pokemon out, and all residual effects will go away after each of these mini-rounds (so Sunny Day won't carry over to the next matchup).

To win the round, you'll need to win 3 out of the 5 one-on-one battles in the round. Since you are unable to switch your Pokemon out, you have little control over the matchups you're giving your Pokemon, so you have to utilize each of your Pokemon's strengths and weaknesses accordingly.

Now, so much of each of these fights are random, and because there is no switching, it is really difficult to provide individual strategy. The one tip I can give you to help would be to analyze your opponent's team. If you see that they have a large weakness to a certain type, but have one or two Pokemon that can counter that type, send out the appropriate Pokemon second. The computer will likely compensate for their weakness by sending out something strong against their weakness first. It's not a proven fact or a science, but it probably makes about as much sense to try it anyway.

Like the rest of my strategies, the strategies I have listed here are for the Blue Rental Pass. You can still apply similar tactics to any of the other Rental or Custom Passes, though.

Try to keep any of your Water- or Rock-type Pokemon out of the fight, if you can.

Harry has lots of Bug-type Pokemon, so try and use things like Monferno, Staravia, and Prinplup first, and keep Grotle out of the fight.

Desiree has an interesting mix of Pokemon. It's really a coin flip for your match ups. Staravia is a solid start, and Grotle and Luxio make good backups. Try to leave Monferno out of this fight, if you're able.

Most of the Pokemon on Sierra's team are weak to Electric-type attacks. Be wary about using Gabite or Grotle in this fight.

Prinplup is great against most of the Pokemon on Ruben's team. Gabite and Staravia will do great as well.

Again, an even split between Grass- and Water-type Pokemon. Hope that you get lucky and choose the right Pokemon for the job. Staravia makes a solid start, because the only thing it will have a problem against is Sealeo.

Last up is Marina. Most of her Pokemon are weak to Electric-type attacks, although she's thrown in a Wormadam and Aipom just in case. If Luxio comes up against Wormadam, you won't be in good shape. The least effective Pokemon for you to use is probably Prinplup (even over Monferno). Monferno can at least handle Wormadam, Corsola (Mach Punch), and Aipom.