trundle7

I can tell you overall best water type that you get only in episode 17. It's Magikarp. You have to find all 4 of the con guy clones and continue the quest to find others. He'll escape into the desert. You have to go in the desert in the place with a ton of trains and you'll come to an area with caravans and people living there. That's where the con man will be. He'll battle you and then leave the Magikarp there so you can get it when you interact with it.

In episode 18 all pokemon are available so use whatever you like best I guess. Maybe Swampert would be good because of the gym leader.