I'm a bit worried about this episode, though... if this is Munchlax's big battling debut, it seems quite likely to me that May will win. But what's the point in bringing Harley back only to have a replay of the Saffron contest? Usually the writers give May different main opponents in every contest per region. E.g., in Hoenn, it went: Drew (Slateport), Grace (Fallarbor), Timmy (Verdanturf), Savannah (Rubello), Kelly (Lilicove), Harley (Izabe), Eriko (Pacifidlog). But now we've got Harley in both Saffron and wherever this upcoming ep is set. It's unusual, that's for sure.
One thing to bear in mind, though, is that IF - and that's a big if - Harley wins, he likely won't appear again until the Grand Festival. Because if the writers give him a victory, it's because they want to build up the tension and make him seem like someone May needs to worry about in the GF. If they have him win now and bring him back later on in another contest, then they can only make May beat him again and the structure will be messed up.
As for Drew, I hope he puts in a showing before too long. Like I said, I think the writers are holding off on the May/Drew stuff at the moment because they want to stall that rivalry for another region… but still. I miss him.