Gardevoir is currently my favorite pokémon, and I've been trying to figure out a way for her to work in competitive play. Do you guys have any ideas?

Gardevoir eh? I think I have a few Gardevoir sets for you.

Gardevoir @Light Clay
Nature: Bold
EVs: 252 HP / 128 Def / 128 SpDef
Ability: Trace
-Thunder Wave
-Reflect
-Light Screen
-Destiny Bond

I've used this exact set for my suicide-lead Gallade when I was once a Psychic gym leader here, and it should work for Gardevoir too. What this Gardevoir does is first T-wave the opponent to paralyze and become faster. After paralyzing the opponent, you have the option to set up screens or surprise the opponent with Destiny Bond. In an ideal situation, you would have the opponent paralyzed and have both screens set up and then use Destiny Bond when Gardevoir is close to fainting. This makes Gardevoir an excellent Pokémon to lead with and give support to the rest of your team.

Is there a particular kind of Gardevoir that you'd want? One that attacks, defends, etc.?

Thanks! I'm definitely going to try this set!
I'm not looking for much in particular currently, but I might let you know if that changes.

I'd suggest Will-O-Wisp over Thunder Wave since it halves attack and Gardevior's regular defense isn't to good.

He said that Thunder Wave's speed reduction was important for the set's efficiency, but I might try both.

You can try an Offensive Gardevoir
252HP/252SpAtk/4Def
-Calm Mind
-Psychic/Psyshock
-Hidden Power Fighting/Dark/Ice
-Thunderbolt

Reun.. This reminds me, now that summer is starting, we should get going with this PotW thing again!

Uh...Gardevoir and Gallade have /always/ been competitive?

Thunderbolt
Psychic
Will O Wisp/Calm Mind
Psycho Cut or Confuse Ray