Looking ahead to end-game, here is my humble suggestion for a team that will cover all of your bases for the E4, working in who you already have on your team :)
Swampert:
-Surf
-Earthquake
-Really, anything you want for the other two slots
Slaking:
-Hyper Beam (you're going to be resting every other team, anyways, right? : P)
-Shadow Ball (Ghost is physical in this gen, and Ghost-type mons won't be able to hit back :P)
-Yawn
-Again, anything that you want
Swellow
-Aerial Ace
-Return/Secret Power
-Double Team
-Steel Wing/Fly (if you don't want to carry around an HM slave for it)
For fighting types I'll give you some options: Medicham or Hariyama. Meditites are only obtainable about 3/4 of the way through the game, so you might not want to wait that long. Hariyama's a great early alternative.
Medicham:
-Hi Jump Kick
-Psychic
-Calm Mind
-Fire/Ice/Thunder Punch (from Move Relearner)
or
Hariyama:
-Brick Break
-Seismic Toss
-Fake Out
-Bulk Up
Rest of the team:
Magneton (New Mauville):
-Thunderbolt
-Tri-Attack
-Thunder Wave
-Anything
Walrein (Spheal found in Shoal Cave):
-Ice Beam
-Surf
-Body Slam
-Encore
Also, in my opinion, it might be best to just drop Vigoroth/Slaking, as it is IMHO just excess weight. If you decide to do that, I would go with Manectric over Magneton, as it has access to Bite to take care of Pheobe. My Manectric set:
Manectric:
-Thunderbolt
-Thunder Wave
-Bite
-Anything