People are really this upset at Ash catching more Pokemon? I for one am glad he's catching more than 5 like the last few regions now. I think the writers have learned from their mistakes in Kanto of how to handle a bunch of Pokemon equally and this saga is going to show it.
So what if it seems Tranquill and Swadloon are being ignored right now? They WILL get their time to shine on his team (hell, Sewaddle/Swadloon got it in the Castelia Gym Battle). Tranquill will evolve by the 6th Gym, maybe in a rival battle against Trip before then, who knows.
Swadloon evolves with happiness, do you honestly believe it will stay as a Swadloon with a trainer like Ash? Don't feed me that 'it's ignored, it will never evolve' crap, because for all we know, the writers have an episode with Ash and Swadloon bonding leading to it's evolution planned for the future before the Nimbasa Gym.
Palpitoad is likely going to stay as Palpitoad since Ash is focused on Oshawott, which in my opinion does not at all hurt Oshawott's chance of evolving.
And, it seems Roggenrola is very likely to be caught, continuing a new trend of stuff Ash never captured before (Dragon-type; Gible, Dark-type; Scraggy, Bug-type (for the first time since Johto); Swadloon). I think the writers purposely gave Trip a Timburr for the reason of them trading an evolving their respective Gurdurr and Boldore down the road.
As for other possible captures, it's really up in the air (even though I think Ash with get a Lampent to balance out the 2 Grass and Waters types), as the writers can give him as many Pokemon as they want whether we, the Pokemon fandom, complain and ***** about a Pokemon not fitting a certain trainer.
I was happy with this episode, Oshawott got development and we got 2 surprise captures. The writers should throw in surprises like that more often. Great episode.