Main Street Colosseum

The Main Street Colosseum is your pretty standard Colosseum experience. There are 7 rounds, it's a Single Battle format, and all Pokemon you fight against will be either at Level 30 or the Level of the highest Level Pokemon on your team (if you're using a Custom Pass).

Unlike the Gateway Colosseum, you aren't restricted to using only Rental Passes, so you can use your team of Pokemon from Diamond or Pearl if you'd like. Just make sure that they're all at the same Level, otherwise your lower-Level Pokemon will be at a handicap.

The strategies listed are assuming you're using the Blue Rental Pass. You can probably apply similar tactics if you're using an in-game team or another Rental Pass.

Luxio and Prinplup should definitely be on your team for this fight. Gabite is also pretty good for a third Pokemon. Have Luxio Spark the Flying-types, and Prinplup use Water Pulse on the Chimchar and Ponyta. Pluck is also good against Butterfree.

Quite an interesting mix of Pokemon around. Staravia will stand a great chance against four of them, with Aerial Ace being effective against Riolu, Machop, Lombre, and Skiploom. Prinplup or Grotle can handle the rest.

Again, Monferno is an awesome choice to use. Between Fire Punch and Mach Punch, you'll score a Super Effective hit on everything but Melody's Machop, which you should be able to overpower anyway. Staravia and Luxio are other good choices.

Luxio is probably your best bet to start with here, followed by Monferno. Between those two, you cover everything except for Chingling, which can be dealt with by other means (although preferably not by Monferno).

Ariel's team is evenly split between Grass- and Water-type Pokemon, so choosing the Pokemon to start with is a coin flip. Staravia and Luxio aren't weak to the opposite type of what they're good against (Luxio isn't weak to Grass, and Staravia isn't weak to Water), but Luxio's Spark isn't effective against the Grass-type Pokemon. Starting with Staravia, then having Luxio and either Monferno or Grotle as back up is a good way to handle the situation.

You probably haven't come up against many Steel-type Pokemon yet in Battle Revolution. They have decent defensive stats and a lot of Resistances, so it can sometimes be tricky to counter them. Monferno can Fire Punch anything on the team to oblivion and back except for Delcatty, which it can handle with Mach Punch, so you'll definitely want to start with Monferno. Prinplup and Luxio are also good choices that get around Steel-type Pokemon's Resistances.

Taylor has an interesting mix of Pokemon in her arsenal. All of them have attacks that will try and inflict you with an assortment of nasty status ailments, so be on guard and try not to dawdle. If you get affected by Confusion or Infatuation, you should switch your Pokemon out for another one to cure it; the other status conditions aren't as easy to fix, though, and you'll be stuck with them for the rest of the fight (except for Sleep). Grotle doesn't really have a weakness to anything on Taylor's side, so it makes a good starter against her. Monferno and Gabite are two Pokemon to consider as backup.