You have a decent physical/special split in your team. The only thing you might lack is a special wall that doesn't require you to set up calm mind.
For the special route:
-Lapras and Walrain have already been mentioned and they are quite solid because they give you ice coverage which is strong offensively while still being on the bulkier side.
-Seismitoad surely brings a lot of coverage as Shinoda Yagami has said.
-Ludicolo, As AnimeFg stated you also lack a grass type, so this one is an awesomely versatile choice, just make sure not to evolve your Lotad until you get Energy Ball at lvl 36.
For the physical route:
-Barbaracle is a decent physical addition which gets access to Shell Smash buffs.
-Poliwrath, I personally swear by mine, but since you already have a fighting type, I wouldn't recommend it and it needs some setup to shine.
A lot of awesome water pokemon have been promised for Ep 16, so if you can hold out until it's here, you'll get an even better selection.
Frillish, Slowpoke, Tentacool, Staryu and Shellder will be added. All of them have their respective place to shine.
Out of the list I'd recommend Tentacool/Tentacruel to you, as it's a beastly special defense wall with a decent speed. It's sure to help you wrestle down Adrienne provided Ame doesn't give his/her/its whole team discharge like she did with Shade.
Cheers