In the long run I find it easier to train Sandile because you don't have to watch it's levels so you get a certain move, like Growlithe. It also evolves three times which is fun. Now in terms of synergy for your team.
Sandile works much better as it gives you someone to hit Ghost and Psychic types. Water isn't a problem as you have Azumarill and Leavanny to take a couple hits, and soon-to-be-Ampharos to check water types. So all good there. In the end I like Sandile/Krookodile on your team.
I'll grab some movesets in a moment here.
Krookodile/Sandile gets a lot of cool moves. Such as Earthquake (Who doesn't like EQ?), Stone Edge, Outrage, Crunch, Stealth Rocks, Swagger, Fire Fang, and Thunder Fang.
Now the simplest yet most effective set to run in-game would be,
- Stone Edge
- Hone Claws/Strength (depending on whether or not you need someone to learn Strength)