Okay, let me see this real quick:
Serperior doesn't have a lot of options by level up, which is bad actually. So just give it Leaf Storm when you can and hope for better TMs in the future. You could give it Coil also for the defence drop ^^.
Since the sun doesn't make a lot of difference for your team, you could change Ninetales. Chandelure is a very good option in place of it, and the coverage really helps. Just a tip though: Litwick/Lampent doesn't learn Flamethrower, and since we don't have the TM, you could breed it with a Slugma/Magcargo to get Heat Wave. It's better than most things in it's movepool, unless you don't care about the Sp. Attack drop from Overheat.
Since there's no way to get Electivire anymore , Luxray is your best bet at "Physical Electric Type" right now. Luxray Sp.Atk is not really that bad though, you could try using a mixed Luxray. But if you're really bothered by Luxray defenses, then you should get a Magnezone. I'm pretty sure Magnezone can take some attacks better than Luxray, and it can at least survive one EQ if you use that Sturdy. But even then, meh. I'm not the biggest fan of physical electric moves, so i'd recommend you get a Jolteon, a Rotom or an Ampharos. Jolteon is fast enough to attack before it takes a hit, though is frail too, so it's probably going to die fast too. Rotom for now is a Ghost, but in the future we're going to get the other forms, so you should look into that. And Ampharos has an awesome movepool right now.
But from what i can see, it's the defenses that bother you, not the movepool. So you can decide what to do by yourself.
You don't like Jolteon? Boo...
Gardevoir is good as always. Nice movepool right now, and nice everything. I don't have anything to say. If you have something to power up Shadow Ball, give it to him, since it's the only move that doesn't get STAB.
Gyarados is destruction, Gyarados is power, Gyarados is the janitor, Gyarados cleans, Gyarados sweep.
The only difference between your Gyarados and mine, is that mine has Strength in place of Bite, but whatever. What can i say, it's Gyarados. Powerful.
You know, we don't need HM slaves. Not now. There's no area like 1st gen Victory Road, so you should drop Linoone unless you want to use it for battles too. You can make a secondary pick up team later, and focus on training them for the pickups.
Recommendation: Your team could use a Ground type, for the coverage. Simple as that. I'd recommend Mamoswine, only because of it's awesome movepool. It's not going to disappoint you. Use it if you can.
As for nicknames, i just sit a while and think: "Okay, what does this pokemon do?" Sometimes i read the pokedex description to give a help with that.