I have a Sigilyph and he's amazing!
His moveset is: Fly, Psychic, Solarbeam and Shadowball.
I also have a Seismitoad with moveset: Uproar, Surf, Hydro pump and Drain Punch.
I think that Conkeldurr is a good choice as it has a very wide range of good moves to learn for example Focus Punch, Stone Edge and Earthquake however it's not the best on coverage.
It would be a good team though if you got the right movesets!