Gardevoir has the ability to read the future. If it senses impending danger to its Trainer, this Pokémon is said to unleash its psychokinetic energy at full power.
– Pokemon Ruby Pokedex
Gardevoir looks rather feminine, yet it has equal chance of being both male and female. Its Japanese name, “Sir Knight” makes it more suitable for male. In Gen IV, the family gained a branched evolution in Gallade, which is male-only, so it makes me think that Gardevoir should be female-only, but I guess it’s hard to do that retroactively, because then what would happen to male Gardevoirs from 3rd gen games…
Anyway, Gardevoir looks like a ballroom dancer, but its Pokedex entries and its Japanese name suggest it’s based on a knight who protects its trainer at all costs.
Stat-wise, Gardevoir has high Sp Attack, good Sp Defense, and Speed.
My Gardevoir in Emerald was awesome. Her name was “Gard”, she has the ability Trace, and has Psychic, Shadow Ball, Double Team, and Calm Mind. When I was fighting the elite 4 Drake the Dragon trainer, I had no Ice or Dragon moves. So I had to use Hariyama’s Whirlwind until I dragged out Drake’s Flygon, then sent out Gardevoir to Trace Levitate. Then I used Double Team 4 or 5 times, so that the chance of getting hit was low. And then use Calm Mind 2 or 3 times, and used Psychic to sweep through Drake’s team, even though Drake’s Pokemon were like 5-10 levels higher than mine. It helped that in Gen III, Dark moves were special, so Crunch was a special attack, which meant Gardevoir could take the hit, especially after using Calm Mind.
In later gens, Gardevoir could learn many special attacks by TM, like Thunderbolt and Energy Ball.