Am I the only one who can see the pertinence of this episode and the focus on Aipom, beyond the comparatively trivial details of whether Aipom will battle Regirock or evolve in the longer run? It will take place after the Grand Festival, but the target from that point on is unknown at present (Scott did not indulge Ash as to the Battle Pyramid's new location). However, we do know this episode will precede the movie premiere - an important fact.
The upcoming movie is of a sea environment, a fact with geographical repercussions. It was easy enough to account for this in the second movie, corresponding to the Orange Islands episodes, but such was not the case with the fifth movie which deliberately tied-in to a small branch of episodes taking place in Cherrygrove City's sea side. Now, the Battle Frontier series was orchestrated in such a way that Kanto's sea parts have already been visited. Therefore, another transition seems to be in order - one that will have to take place in the Aipom-centric episode.
Aipom appears to be the symbol of this transition; the very fact that Ash is to capture any Pokémon at a time considered to be the end of the AG series, is one worthy of attention. It is in every way likewise to Phanpy's return last year - completely against the expectations of the average viewer who would expect a transition from third generation Pokémon to newcomers of the fourth. I wish I could say the same for May's Squirtle and Eevee, but their being veteran Pokémon falls short to their popularity factor, and so it the latter to which their acquisition is ascribed.
Granted, Aipom is distinct from Phanpy in that it is only making its arrival now. It goes without saying that Diamond and Pearl were not to see release last year as so many had expected, but the same will not be repeated this year. Yet, rather than stretching the Battle Frontier journey and showcasing Aipom at least before the Battle Tower, its place has been reserved for the very climax. That seems to shed an interesting light for us yet again - Phanpy essentially marked the continuation of the AG adventure in the form of Kanto and the Battle Frontier, as opposed to dwelling on the Hoenn League until the time has come for the new generation. Aipom is very much the same, which currently serves to open many questions.