I've given Magcargo a try in OU before, so I can give you a bit of advice here.
Lava Plume is a must over Flamethrower. Magcargo is not going to be doing much damage anyway, and since you're trying to increase the chance of Burning with Flame Body and stuff, you can add another 30% burn chance by using Lava Plume. It works very well considering you don't have Will-O-Wisp on this set, so it gives Magcargo a better chance to support the team.
- I don't see any use in will-o-wisp for macargo, since other fire types use it much better. I do see the potential in lava plume though.
Do not ever use Endure on Magcargo. Seriously, it really needs Recover very badly, otherwise it has only a 30% chance of doing something, and a 70% chance of doing nothing. Recover at least lets it abuse its good resistances to some extent. It also allows it to wall on both sides when Sandstorm is up, because Magcargo's Special Defense gets a huge boost in that. You might even want to consider throwing in some Special Defense EVs, but I suppose that if you have Light Screen already, then you don't need Special Defense EVs. I'd highly recommend Light Screen over Reflect for that reason.
- I myself never used endure on Magcargo(I've only tested Recover). I just wanted to see the response, since it can be an option. Even after it's used, if you can switch in safely, without rocks or spikes, you can endure attack after attack. Obviously, this is extremely difficult to accomplish, but I just thought it could be an option. And I see little utility in special defense EVs, since this magcargo is supposed to almost exclusively switch in on physical attacks, or special attacks that don't scratch it at all. Light screen is if you lack special attack absorbers in your team, but I've been using Reflect to boost Magcargo's ability to switch into physical attacks.
To be perfectly honest, AncientPower is an awful move on Magcargo. Sure, it gets STAB, but with 8 PP, and only 60 BP, there are a lot of unSTAB moves that are even stronger than it. For instance, Earth Power, which is better in almost every way, besides the possible haxy boosts, that really do not help Magcargo anyway. I personally wouldn't even recommend using Earth Power though. I'd recommend using Yawn in that slot, which, in my opinion, is a must on every Magcargo being used in OU. It helps him support the team so much, and it can also prevent him from dying horribly to a threatening opponent that wants to come in and capitalize on one of Magcargo's weaknesses, since they'll either have to switch out, or fall asleep next turn. While those things are switching out, it also gives him some time to use Recover, or set up a screen, which is even more support.
- Yawn is an option, but it could do down instantly if the opponent decides not to switch. So, I've been switching this magcargo in and out alot, pairing it up with another rarely used poke, Parasect! :D *Rapid spinner needed* Rather than sleeping in coming water types, I'd capitalize on their water attacks, healing parasect. Rock and Fire is rare but useful combination, and magcargo is the only poke to get the double stab. Camerupt uses Earth power better.
Finally, I'd recommend using Leftovers over Light Clay. Magcargo may not be able to find the time to use Recover due to 25% stripped off due to Stealth Rock damage right when he comes in, but if he can't use that, he can at least get some healing from Leftovers to turn many of the 2HKOs against him into 3HKOs, which he can then shrug off easily.
- I personally find 6% way too middling to really help. But it could be a second option.
Yeah, that's what I have to say on it, since I've loved using Magcargo in OU for a long time, so props for using him. :]
-Thanks for your thoughts.
