If you want to try be more annoying, Wobbuffet is especially good, although a strong Dark attack probably can still wipe it out.
2 sweepers and 1 wall would work nice, but it depends what type battles you plan to do.
No matter what, try cover as many bases as you can, play to your strengths and try remember the opponents general weaknesses. Can always load up a few Bulbapedia tabs for quick searching on some of the basics.
As for not using Electric/Normal, well Electric types are horrible, but you could give a few electric moves to those who can make a dent with them. Normal isn't all that bad though if you don't have interaction with other people/games (to be able to get a pokedex entry and hence GTS trade, I haven't WiFi battled much, but I don't recall the opponents pokemon counting to your dex).
Mainly though, try get at least one STAB for each of your pokemon that you intend to do damage with. Sweepers STAB is almost a must, Walls don't necessarily need STAB, but it certainly can help.
If your sweeper can, make it learn a move that would be super effective against the type you're weak to. Same goes for most of your team in general.
As for Medicham, I'm thinking a good STAB'd Ghost move will be able to take it out in one shot. Could pack a Dark move to counter the Ghost types.