I have what I think to be a good sweeping moveset on my own Ampharos, so I'll list that, as well as a few choice moves for the other Pokémon - the rest is up to you to fill in the blanks.
Typhlosion (Some high-damage Fire-move, Brick Break, etc. etc.)
Skarmory (Drill Peck, etc. etc. etc.)
Ampharos (Thunder, Signal Beam, Power Gem, Rain Dance)
Scizor (X-Scissor, etc. etc. etc.)
Gyarados (Aqua Tail, Earthquake, Ice Beam, etc.)
Umbreon (Curse, Payback, etc. etc.)
As for a breakdown of why I chose these:
-Typhlosion fills the fire spot, but also has access to Brick Break which is a good, solid fighting move.
-Skarmory has access to Drill Peck, which as far as I can remember is one of the strongest Flying type moves it has access to.
-Ampharos' moveset listed is my current set for it; it can be a bit dangerous trying to setup Rain Dance to get 100% accuracy on Thunder, but it's nice when you can spam Thunder over and over :)
-Scizor can really rock the move X-Scissor (although if he has the Technician ability, Bug Bite is even better, though that one requires BP to move-tutor it)
-Gyarados I don't have much experience using, but earthquake would really play hell with electric types trying to ruin his day, especially since it can draw power from his really high attack stat.
-Umbreon is one of my favorites and really pulls off the combo of Curse/Payback really well.
Also, with the limited movesets I listed, you have at least 1 move to counter every type in the game.
# Moves Supereffective Against a Given Type:
I hope that helps, as well as leaves a bit of room for your own personal touch to the movesets. I would definitely recommend some more damage-dealing moves to cover some of those types with only a single move to deal with them, but that's up to you.
Pokemon Y Trainer: Satsuki - Friend Code: 5086 1956 4651
Black 2 Trainer: Leia - Friend Code: 4084 3320 5448