Well, the drawing-style in this episode wasn't that good, but the hilarity quite made up for it in my opinion^^ My favorite moment was when May said "Son'na banana" instead of "Son'na bakana", that was very funny.
Nice to see a comeback of Slakoth, Vigoroth and Snorlax. And that cool BGM from AG 91 that is played so rarely was in there too (For some strange reason, I saw AG 91 before this one)!
One minus point was that Slakoth's battle-and-evolution-scene, it was too rushed and a bit unrealistic generally. On the other hand I can understand that the the writers hadn't had the time to make it any longer, especially since the battling was not the focus of this ep.
So, overall I think this episode was quite good.