I knew this was an Iwane episode right from the very first minute - Satoshi and Kasumi's argument is brilliantly animated. Furthermore, Musashi-tachi have some hilarious facial expressions throughout, including that "oh crap" look that Musashi and Nyasu get when they realize Kojirou's already in the phone booth. And it goes without saying that Takeshi's romance-fueled fits of chivalry in his efforts to find Joi-san are virtuoso pieces of work.
The battle in Act II is downright epic, due in no small part to Iwane's stellar direction. Pikachu and Fushigidane and Zenigame and Lizardon vs. Arbok and Matadogas and Beroringa and Utsubot is probably one of the highlights of the series. I especially like the in-joke that comes at the end, where the four Rocket-dan Pokémon get blasted off separate from their trainers, and they all emit a four-syllable cry that's obviously supposed to be Pokémon speak for "Ya na kanji~!"
Utsugi-hakase is really funny, mostly 'cause you get the sense that he's drastically under-qualified for his job. Note that Ookido-hakase refers to him as "Utsugi-kun", meaning he clearly doesn't consider the guy as an equal. And I should mention that Waninoko's voice is adorably funny. "Wajiwajiwajiwaji..."
While I'm here, I might as well bring up the opening theme. "OK!" is easily one of my favorites. Every time it comes on, I completely forget that Jouto was full of boring, inconsequential fillers - this song puts me in the mood for adventure, no matter what! That part in the middle with the five synthesizer hits and the hyped-up shout of "HAI!" leading into Satoshi singing "Golden Sun and Silver Moon"...that's adrenaline, man. Oh, and I can't overlook "Nyasu's Party", the ending theme that launched with this episode. It's so delightfully goofy - and hey, anytime Inuyama Inuko sings as Nyasu, it's hilarious.