Kirlia is a ballerina, Gardevoir a ballroom dancer, visually. I wouldn't call her a knight though.
Gardevoirs appearence is a young person wearing what looks like to be a ballroom dress, which people confuse on why she is called a knight. Well, you may want to explain why her face has portrusions and curls up in mega form. They're a representation of a knights mask. I'd say the dress looks more like capes, actually. That's why the middle of her 'dress' is parted, and you can see hints of legs beneath the layers. Although, she can be based of a knight mage, as the other poster said. Her 'dress' could very well look like the White Mage from Final Fantasy. :P
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