R/S/E Crafting a new Battle Frontier team

So, I haven't gotten very far in the Battle Frontier, and I think it is because I haven't been able to craft a good enough team. I have a few existing Pokémon to use and a few that I've been planning on raising. So, here is what I have at my disposal:

My old Frontier team. I like the movesets but I didn't know anything about EVs and natures said:

Kingdra @ Leftovers
Swift Swim / Bashful
~ Surf
~ Rain Dance
~ Return
~ Ice Beam
Level: 59
HP: 188
Attack: 140
Defense: 143
Sp. Attack: 135
Sp. Defense: 129
Speed: 124

Alakazam @ King's Rock
Inner Focus / Bold
~ Psychic
~ Recover
~ Roleplay
~ Thunderpunch
Level: 59
HP: 163
Attack: 66
Defense: 93
Sp. Attack: 190
Sp. Defense: 125
Speed: 166

Magcargo @ Focus Band
Flame Body / Docile
~ Flamethrower
~ Rock Slide
~ Sleep Talk
~ Rest
Level: 56
HP: 138
Attack: 74
Defense: 153
Sp. Attack: 109
Sp. Defense: 108
Speed: 74

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I'd like to keep Kingdra on my team because I like its relative lack of weaknesses and its strong attacks. I may replace Thunder with Return; does this seem like a good idea?

I might replace Alakazam with a Metagross using Meteor Mash, Earthquake, and Return (if I remove it from Kingdra). Then I'm not sure what to do for the last attack; Metagross would probably wield Psychic well, but I have Kingdra for special attacks. Iron Defense, maybe? Or is Psychic the better option?

Also, what kind of nature would suit a physical-move-using Metagross? Adamant, maybe?

Possible Pokémon so far? said:

Kingdra @ Leftovers
Swift Swim / Bashful
~ Surf
~ Rain Dance
~ Return
~ Ice Beam
Level: 59
HP: 188
Attack: 140
Defense: 143
Sp. Attack: 135
Sp. Defense: 129
Speed: 124

Metagross
Clear Body
~ Meteor Mash
~ Earthquake
~ Return
~ Psychic / Iron Defense

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Then, I'd like to replace Magcargo because it has so many crippling weaknesses. I was thinking of replacing it with a Pokémon using Wish and Baton Pass. I narrowed it down to Togetic or Eevee.

It would require insane amounts of planning and breeding, but here's my idea for Togetic:

Togetic said:

Togetic
~ Wish
~ Baton Pass
~ Substitute
~ Psych Up / other?

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But then if I raised an Eevee (and again, it would take insane amounts of planning and breeding), I could evolve it and have even more options. I think an Umbreon because, of the options, it has the best defensive stats, and I don't want my Wish/Baton Pass Pokémon to faint before I can use both moves. Here's my idea:

Umbreon said:

Umbreon @ Quick Claw
Synchronize
~ Wish
~ Baton Pass
~ Confuse Ray?
~ Substitute / Psych Up / other?

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I'm leaning more towards Umbreon than Togetic. Maybe either Timid or Jolly for it?

So, Kingdra/Metagross/Umbreon? Any suggestions?

(if you read this whole thing, thanks! =D)

Alakazam with 66 Attack and Thunderpunch?
Really.

This is in Emerald; Thunderpunch is a Special attack. And in any case, I'm replacing Alakazam, so it doesn't really matter.

You mentioned in your old team description that you didn't understand EV's, natures, and so on; is that still the case for your new team? I see you asking about natures, but if you mentioned EV's I missed it. You listed your pokémon's stats, but that's really not very useful. I'm afraid that you can build a team with the best pokémon in the world, in terms of strategy and type balance and so on, but if you do not EV train them properly you will never do very well in the Battle Frontier. You can throw together random-EV'd things just to test out how well the team concept works, but for the final production you're going to need every stat point you can scrounge. So, the absolute first step is to get EV's, IV's, and natures locked in, if you haven't already.

Beyond that, your team is nice and bulky, and kingdra and metagross are more or less okay (but replace kingdra's return with something dragon-typed for preference; it looks ilke it wants to be an all-special attacker). I'm not sure a wishpasser is really what you want for your last slot, but if it's between umbreon and togekiss and you look at a comparison of their stats, I think the choice becomes pretty clear.

Your wishpasser should have at least one offensive attack so that it's not utterly hopeless if taunted or your last pokémon standing. Crunch if umbreon gets it, or faint attack if not. Confuse ray is quite useless in the Frontier, and umbreon doesn't make very large substitutes... but they would at least help both your pokémon to some degree, so use that unless you would prefer curse to pass to metagross. Neither timid nor jolly makes sense for umbreon--the point is for it to be a tank, so speed matters almost not at all. Pick something that boosts one of his defenses instead (I would go special myself) and deducts from attack, since it's utterly worthless for him.

I think I understand it much more than I did before. I would want to EV train Metagross in Attack for sure, and perhaps Speed? Some of the articles I was reading seem to advise against training in defensive stats and I can see why.

Had I been able to EV train Kingdra, I would choose Special Attack and Speed. But Kingdra can still level up quite a bit; couldn't I use Kelpsy, Qualot, and Grepa berries to remove their EVs and raise Speed and Special Attack's EVs more?

That makes sense about Umbreon's moves and natures. I'll keep that in mind if I raise an Umbreon for my team.

I'm not sure a wishpasser is really what you want for your last slot

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What else would you (or anyone) recommend? I already have Special and Physical Attackers (would they be classified as sweepers or tanks?). I've been looking at some lists of competitive battling roles but I'm not sure what to fill the gap with.

As for IVs, I don't really know how to use those.

I'm not exactly sure, but based from inference, I think sweepers are the ones that can dish out a ton of damage but can't take much, and the tanks can give and receive.