Serperior
There is not much to change here since you have the classic Contrary sweeper. Replace Hidden Power Rock with Hidden Power Ground because it covers most Types you can't normally touch(Fire, Steel, Poison). Or Hidden Power Ice(Dragon, Flying). Other than that, nice.
Togekiss
Okay, Para-Flinch Togekiss. You really want to have bulk to perform well with it, so I recommend that you change the Nature to Calm Nature(-Attack +Sp. Defense) and change the EV spread to 252 HP, 146 Sp. Attack, 110 Sp. Defense for some bulk. Togekiss needs to take hits really good, so that should be good. The Moveset is really good so no problems with that. EDIT- since you now need a bulky Fire type, I suggest Heatran as a tank since it does it really well:
Heatran@ Leftovers/Air Balloon
Calm nature(-Attack +Sp Defense)
EVs:252 HP, 128 Sp. Attack, 98 Sp. Defense, 32 Defense
- Lava Plume
- Roar
- Earth Power/HP Ice
- Will-o-Wisp/Torment
Your Tank leaves a Dent while taking a few hits! Roar is used to make it a phazer with SR. Lava Plume is STAB with a high Burn Chance, making your Walling capabilities more possible. Torment stops Choiced Pokemon. Earth Power is Coverage as is HP Ice. Try it out.
Torkoal
Torkoal doesn't seem to contribute much in the team, since it cannot take a hit, weak to Stealth Rock, and terribly slow. So I suggest you replace Torkoal with Claydol. Here is a good support set and EVs.
Claydol@ Leftovers
Impish Nature(-Sp. Attack +Defense)
EVs- 248 HP, 188 Defense, 37 Sp. Defense, 37 Sp. Attack
- Rapid Spin
- Stealth Rock
- Earthquake
- Toxic
As you can see, Claydol Also Rapid Spins and thanks to its Bulk, it does it way better than Torkoal. It also resist. SR and can support Pikachu with Levitate. It can also set up its own SR's!
Azumarill
Not much to say here either. Just replace Rollout with Aqua Jet so it can be an amazing Revenge Killer.
Replace the Spread to the simple 252 Attack, 252 Speed since it does not have
Pihe Bulk to set up.
Pikachu
I have a problem with this one, because Pikachu is extremely frail, so I suggest you replace it with Jolteon with this set:
- Thunderbolt
- HP Ice
- Wish
- Shadow Ball
This set is your basic Wish set without. Baton Pass. Shadow Ball supports Togekiss and Claydol, who struggle with Ghost Types. Wish Supports all Pokemon in need of HP. The rest is STAB and coverage.
Magikarp
As the others say, take out Splash because if you get into a war with your Opponents Magikarp, you get to Struggle faster than them. Replace the Focus Sash with the Fish stick(LOL).
Have fun with your Team :D