Ok, I've decided I want Ekans and Carvanha
About the episode, I could only find it in RAW so I didn't understand much, Jessie says something about Pikachu. It sounded like "at the end we never caught Pikachu", but I got that from the way she said it, the only word I understood was "Pikachu" xD
It is suspicious that the ending was their theme, but if it was their last episode, it was the worst Good-Bye Episode I've ever seen. I hope don't they just ditch them like that. Oh, and I can't believe they showed scenes from every season, but they didn't show Arbok and Weezing >:l
But you may be right, this could be their last episode only in Unova. Ash is about to challenge Drayden, so the League is next and Unova will be over. After that there might be some filler, or maybe they'll announce the next gen game next year, but it's still too soon for that, especially after they just released B2W2. This is how predictable the anime is xD