It is worth using a CTM on AT Vap?

Aqua tail is fine. I wont bother personally.

Against SoB AT might actually be better. I wouldn't change.

Keep it, I have both and they perform nicely.

No. Water Pulse, that's another matter. But both Hydro Pump and Aqua Tail are solid performers, with Aqua Tail trading a little overall damage for a lot of convenience of use.

My strongest Vaporeon has AT, and the next 5 in CP have HP. Probably wouldn't want to switch that, but glad I have one solid AT to go along with the Fire Brigade. Keep it as is.

Naw, with weather boosts the bosses have been pounding mons so getting 4-5 AT off is better than 1 HP and it’s much easier to do than try and get 2HP off. Plus it’s a way more useful/energy efficient gym attack.