Actually it taught us again that anime Pokemon don't evolve by trading.
While there were a couple of trades in the anime, the writers realized that it would be ridiculous to have Pokemon trade-evolve like in the games. Why? Because that would mean having to give your Pokemon to someone, and by doing this, what's they say they wouldn't take the Pokemon and run? The writers came up with an idea that using the Pokemon center teleport system would work like trading(they did this before, with Misty's Poliwhirl).
It makes sense, since the trade center remains in a Pokemon center.
While I admit that they could have had the two kids trade their Pokemon back and forth, the writers probably didn't want to use that(although they said that at the end that people were trading their Pokemon) so they used the shtick that Misty's Poliwhirl went through when it evolved to Politoed.
I did hear about the change of the attacks in the end of the second battle. Not that I am complaining - I'm getting sick and tired of Pikachu zapping Team Rocket until they are blown away with thunder attacks. Of course, I did see the edit a bit now that I heard about it.