Buu, I love your opinions....most of the time. Crawdaunt is HUGE on an all water team. Go with this. I use it, it's not on an all water team, and it works!

Crawdaunt @Scope Lens
-Crab Hammer
-Aerial Ace
-Brick Break
-Body Slam (I know it's an egg move, but its worth it!)/Facade/Return

I would use this, but instead of droppin your Walrein tank, drop Pelipper. I know that you're probably thinking I'm a moron but hear me out.

Crawdaunt here can't learn Earthquake, so you need someone here that still does. He can learn Aerial Ace which takes care of the flying move, and drops the 2x weakness of Pelipper. Scope Lens to help w/the CH Critical Hit Ratio. It's attack is also HUGE so it doesn't need Swords Dance.

Hope this was of some help. The rest of Buu's opinions are fine IMO.