Ludicolo,Swampeet, and Lanturn.
Water+Grass makes a great combo, eliminating all of the special weaknesses. They do get rid of resistances, but no electric, grass, ice,and fire weakness helps a lot.
Swampert- The sole reason electrics carry hidden power grass. it has only one weakness to a less common type and immune to a common type.
Lanturn- Can blast other waters and defend well enough.