Gallade, for Dawn? What makes you say that! Gallade seems far too manly and focussed for Dawn, like some kind of elite warrior, I can't see that suiting her at all haha. She's already got Mamoswine as the token "conflicting personalities" Pokémon so I'm not sure where Gallade would fit in and although it'd be interesting to see, I can't really think of a way that they could make it work... I'd love to hear your reasoning though!