Now now, I wouldn't go that far. It was definitively the best theme deck in at least a decade when it was released. Most people agree now that it's been surpassed, and it's possible some very old theme decks had some quality to them (obviously accounting for power creep. I've heard say that theme decks used to be better, but not exactly from a reliable source). But certainly it deserves more respect than 'mediocre.'
Besides, I haven't had a challenge that it could clear better than another theme deck since it became available. Its best Fighting damage ****** is probably a hippo and its evolution is dragon-focused. So the best use of it is definitely not challenges.
"Swishonk!" That's what's happening!