What you see is what you might not battle.
Pokemon X and Pokemon Y's Free Battle matches allows you to choose three of the six Pokemon in your party. Since most Pokemon Trainers are more gullible than Kelly Bundy from the classic Married... with Children TV series, you can use fear tactics to manipulate those Trainers.
A Level 1 Aron is feared in the Pokemon community because a Sandstorm followed by that Pokemon can sweep an entire team as seen in the video below:
Here's a rundown of that Pokemon:
Pokemon: Aron.
Level: 1.
Ability: Sturdy (cannot be knocked out with one hit).
Item: Shell Bell (restores 1/8th of the damage it inflicts on its opponents).
Moveset:
- Endeavor (reduces targets HP to that of the user).
- Toxic (gives Aron something to use against some Ghost-types).
- Sleep Talk (allows Aron to use a random move if put to sleep).
- Protect (stops Fake Out)
Since Endeavor will leave your opponents with 1 HP, you'll need to setup a Sandstorm before you bring out Aron. A Sand Stream (creates an instant Sandstorm when first entering a battle) Tyranitar that's holding a Smooth Rock (extends the Sandstorm from five to eight turns) is a fantastic lead.
Since that strategy is deadly, you can take advantage of your opponents by using fear tactics.
I've been experimenting with having Tyranitar and Aron in my Party, and I found that fifteen of my last seventeen opponents started the match with a Pokemon that can counter Tyranitar, and followed that by bring in a Pokemon that can counter Aron.
Popular Pokemon that can counter Tyranitar includes Garchomp, Groudon, Infernape, Kyogre, Lucario, Machamp.
Popular Pokemon that can counter Aron includes Mega Kangaskhan, any Ghost-type Pokemon, and any Pokemon that knows a multi-strike move (such as Bullet Seed), or any Pokemon that knows Knock Off (removes the target's held item).
Since I found that most of my opponents started the match with a Pokemon that can counter Tyranitar, I figured that it would be fun to troll those Trainers by bringing out a Pokemon that can counter most Pokemon that can counter Tyranitar, such as Dragonite or Latios.
I also trolled those Trainers by choosing a Pokemon that can counter most Pokemon that can counter Aron in my team, such as a Dark Pokemon.
That strategy allowed me to win fourteen of the fifteen matches in which my opponents prepared for Aron. Sneaky, huh?