A good rental pass to start with is Nate as he has the latest and strongest starter Pokemon as well as some other good ones. Cyndy is ok but choose Nate, he's better.

If you have good pokemon in Pokemon Diamond or Pearl you can tade them to Pokemon Battle Revolution by trading them to Battle Revolution.

If you are having trouble on 1player mode you should obtain a togekiss that has the serene grace ability in diamond or pearl & teach it air slash,thunder wave,aura sphere,& roost & use it in all battles that allow you to use custom passes.first use thunder wave for paralyzing,then use air slash & since it has serene grace there's a 60% chance it'll flinch plus 25% of paralyzation,so your foe can barly attack you,& you can use aura sphere to finish off opponents since it all ways hits & roost is self explanitory.togekiss helps alot especially on the final colluseum.

If you can't bet the sunset colossem here are some hints:

1.) You can pick from your opponent's pokemon

2.) Hit B before you pick a Pokemon to check it's moves.

3.) Don't loose a Pokemon on the first three battles. If you don't you get
Continues when you loose.

4.) On the final battle (I don't know if you get the same Pokemon for all games but,) pick Vigoroth, Grovyle, Riolu, and Gabite.

To get the crown you have to beat the stargazer colluseum. Also once you beat the stargazer colluseum you will be able to transfer a pikachu that knows surf to your Pokemon diamond or Pokemon pearl.

Pokémon Battle Revolution is set for released on June 25th, 2007.