I don't think it hurts Popplio all that much, as it can still get Water Pledge for the power, and now gets Icy Wind to help its coverage options.I understand the late availability of scald hurts Popplio and Wingull badly, but does it even hurt Gyarados enough for it to lose its S tier status? Gyarados's special attack is so weak that ice fang is usually stronger than scald. On the topic of S tier differences, why is Oricorio so much better now than it was in SM?
Also, I think Feebas should be listed with a (trade) next to it just for clarity.
As for Oricorio, it's likely thanks to a MUCH earlier Flyinium-Z. (you can now get it on your first visit to Ten Carat Hill by heading north) Having a STAB nuke shortly after getting Pom-Pom Style seems to be of great help, especially when you've a slow Water/Bug Totem to unload it upon on the next island. It'd probably help to read the arguments for Oricorio to understand its placement.