Fennekin event was removed in version 6 iirc, replaced with Ditto, which has the same spots as Fennekin found here: http://www.pokemonreborn.com/forum/index.php?showtopic=14712&hl (Missing Boyfriend sidequest), unless you're in V5. But anyways, Mudkip I can't remember the EXACT details of it but just wander around Wispy Ruins, it'll eventually go back to it's starting position.