OK, so this is my first post, so please be kind...
I've been running
Magnezone: Assault Vest
Ability: Analytic
Nature: Quiet (+SpA -Spe)
IVs: 30/x/31/31/31/0
EVs: 252 HP/ 252 SpA/ 4 SpD
Volt Switch
Thunderbolt
Flash Cannon
Tri-Attack
Essentially, I like to have something that can tank a hit and then volt-switch/u-turn out into something else. Moreover, my team has very little to threaten either water or fairy types and 'zone fits the bill. This particular pokemon came to me shiny while I was IV breeding, and I'm not sure about how concerned I should be with the -1 HP IV.
How it's worked so far: Magnezone's typing with the AV means that it can survive several non-supereffective hits. Moreover, the high SpA and Analytic means that it can launch some really damaging volt-switches while providing a clean switch-in. It also serves to bait out pokemon that have problems with my other team members (typically Gyrados, Garchomp, and Azumarill).
Questions: First off, does one HP IV matter that much?
How about my move list--I'm generally unhappy with all of the non-volt switch moves, but it has so little to choose from. Tri-attack is in there to give neutral coverage for electric types, but it doesn't do much else. It has access to Hidden Power (psychic), but I don't see how that helps me.
Other pokes that might work? I've tried Scizor, but, he didn't seem to hit very hard with the AV and his moves weren't really offering me any coverage I didn't already have on the team.
Any insight is much appreciated!
I'd run it with Signal Beam over Tri Attack. You won't be able to hit Rotom-H or Camerupt for neutral damage, but you'll be able to hit significantly more pokemon for super-effective damage. Also it's a transfer-only move, so you'd have to have this guy in B2W2 if this isn't for something like Pokemon Showdown. Tri Attack is a good enough alternative if you have no access to B2W2 though. When I ran a similar set on Pokemon Showdown, I ran Air Balloon over Assault Vest, since Magnezone is such Earthquake bait thanks to 4x Ground weakness, and it's not like Ground attacks are especially uncommon in the upper tiers. If you run Hidden Power, Fire or Ice would probably be the most use, but it'd be far from convenient to get since you'd have to rework your IVs for that.
As for the EVs, no, one single HP IV shouldn't hurt you in the long run unless you have a pokemon with a weakness to Rock, in which case you'd need to adjust EVs to ensure it has an odd number of HP. Magnezone resists Rock, so it's safe to switch into a Stealth Rock for the most part.
If you're willing try others, these two might be options:
Probopass @ Air Balloon/Choice Specs/Assault Vest
Sturdy/Sand Force
Modest
252 HP, 252 SpAtt, 4 Def/SpDef
- Power Gem
- Earth Power
- Flash Cannon/Dazzling Gleam/Hidden Power
- Volt Switch/Hidden Power
This thing actually has pretty beastly defenses in both categories, so Assault Vest might well be pointless as you'd have diminishing returns from it; I'd go for either Air Balloon to mitigate its 4x Ground weakness or Choice Specs to allow it to actually hit for some decent damage. If you have anything on your team running sand, Sand Force will be your ability of choice, since it'll buff Power Gem, Earth Power, and Flash Cannon; otherwise, either of its abilities could work, since you'd be able to trap a foe's Steel type and take it down with Earth Power using Magnet Pull, or survive against a Lucario or other strong Fighting or Ground type and counterattack if you have Sturdy.
You'll note that I didn't include a type for Hidden Power, and that's because there's a large number of types that could be used to round out its coverage to complement the already-great coverage from Power Gem and Earth Power. If you choose to give up Flash Cannon, you could try Fire, Ice, Poison, Fighting, Bug, Flying, Ghost, or Dark, and any of those will let you hit the great majority of pokemon out there for SE damage. However, this may not be worth it since anything you could hit for super-effective damage with HP you could probably outdamage with a neutral Flash Cannon. If you opt to replace Volt Switch instead, you'd be able to work well with Grass, Ice, Flying, or Bug, and while you'd hit a few less things for super-effective damage, you won't lose out on the boost from Sand Force as much by skipping Flash Cannon. You would be losing the original purpose of having a slow Volt Switcher, though. Even forgoing Hidden Power isn't a bad choice, since those four moves do cover a fair number of pokemon for super-effective damage, and has perfect neutral coverage. If you wish you could also take Dazzling Gleam to help him take down Fighting types, though he wouldn't be improving his coverage very much if he took it over Volt Switch. If he went for Power Gem/Earth Power/Dazzling Gleam/Hidden Power, though, he could feasible go with HP Fire, Grass, Ice, Fighting, Poison, Flying, Bug, Ghost, or Dark, all of which would give you absolutely amazing coverage. If you're willing to give up coverage and can go for a transfer move, you could get some recovery via Pain Split, but you'd also be forced to use Air Balloon or Lefties for him.
The two downsides are pretty obvious, though. First, Probopass trades in Magnezone's Fire weakness for Water, and he's far weaker to Fighting type hits, which isn't so bad, but he's also trading Magnezone's eleven resistances for eight himself, losing resistance to Electric, Grass, and Steel, which is a bit of a blow to his survivability since the first two of those are very common types. Second and more importantly, he's hitting for far less damage than Magnezone can since he has just a little more than half of Magnezone's SpAtt, relying on having a super-effective move to use against the opponent, as well as the damage buff from Specs and/or Sand Force. He could be effective with a Life Orb or Expert Belt, but the former is counter to his defensive nature while the latter isn't an especially strong buff and still leaves him relying on being able to hit the opponent with a super-effective move. The latter of these issues is somewhat mitigated, though, by the fact that he
can hit a large number of pokemon super-effectively, and doesn't need to have a move transferred from another generation to do so. Still, I'd have to run some calcs to see how much the damage changes between the two.
Porygon2 @ Eviolite
Analytic
Modest/Quiet
252 HP, 4 Def, 252 SpAtt
- Tri-Attack
- Recover
- Ice Beam
- Shadow Ball/Thunderbolt
This guy has a bit of advantage over your Magnezone since he's capable of healing himself with Recover and can utilize Eviolite, which gives him the same buff as Assault Vest on both defenses, while not limiting him exclusively to attack moves. Aside from Recover, he gets pretty much the same type of coverage as Magnezone does with his moves. If you want to maximize the number of pokemon he'll be outsped by, running Quiet and having 0 Speed EVs is an absolute must. You can, however, run Modest to be able to do a little more damage regardless, costing you the ability to get the Analytic boost against slow pokemon. Shadow Ball and Thunderbolt give you pretty similar coverage when combined with Tri-Attack and Ice Beam; with Shadow Ball, the only thing you can't hit for at least neutral damage is Bisharp but cost you a small handful of pokemon you can hit super-effective, while Thunderbolt will leave you walled against Magnezone and Shedinja, but give you a few more pokemon you can damage super-effectively.
The biggest downside for Porygon2 is its typing. Normal is not a good defensive typing, resisting absolutely nothing, so it has to rely on its improved bulk via Eviolite and Recover to keep it alive. It's also vulnerable to Toxic, but is hurt less by Burn due to its ability to Recover. It has slightly less SpAtt than Magnezone too, but it's not nearly as crippling a drop as you'd get from switching to Probopass. Also, its lack of access to Volt Switch robs your ability to do slow-switching. The fact that it's an unevolved pokemon also makes it Knock Off bait, which could be a positive or negative, depending on if you have a pokemon that can take advantage by either resisting a Dark move or having Justified.
-----
Aight, went ahead and did those calcs

Here's the results I got versus a few threats, using the moves that're most effective on them:
252+ SpA Analytic Magnezone Flash Cannon vs. 252 HP / 252+ SpD Florges: 200-236 (55.5 - 65.5%) -- guaranteed 2HKO after Leftovers recovery
252+ SpA Analytic Magnezone Thunderbolt vs. 4 HP / 0 SpD Talonflame: 570-672 (191.2 - 225.5%) -- guaranteed OHKO
252+ SpA Analytic Magnezone Thunderbolt vs. 0 HP / 4 SpD Mega Lucario: 280-330 (99.6 - 117.4%) -- 93.8% chance to OHKO
252+ SpA Magnezone Thunderbolt vs. 252 HP / 4 SpD Azumarill: 390-458 (96.5 - 113.3%) -- 75% chance to OHKO
252+ SpA Analytic Magnezone Flash Cannon vs. 4 HP / 0 SpD Garchomp: 214-253 (59.7 - 70.6%) -- guaranteed 2HKO
252+ SpA Sand Force Probopass Flash Cannon vs. 252 HP / 252+ SpD Florges in Sand: 138-164 (38.3 - 45.5%) -- guaranteed 3HKO after sandstorm damage and Leftovers recovery
252+ SpA Sand Force Probopass Power Gem vs. 4 HP / 0 SpD Talonflame in Sand: 708-832 (237.5 - 279.1%) -- guaranteed OHKO
252+ SpA Sand Force Probopass Earth Power vs. 0 HP / 4 SpD Mega Lucario in Sand: 260-306 (92.5 - 108.8%) -- 50% chance to OHKO
252+ SpA Sand Force Probopass Power Gem vs. 252 HP / 4 SpD Azumarill in Sand: 156-184 (38.6 - 45.5%) -- guaranteed 3HKO after sandstorm damage
252+ SpA Probopass Dazzling Gleam vs. 4 HP / 0 SpD Garchomp: 154-182 (43 - 50.8%) -- 3.9% chance to 2HKO
252+ SpA Choice Specs Probopass Flash Cannon vs. 252 HP / 252+ SpD Florges: 158-188 (43.8 - 52.2%) -- guaranteed 3HKO after Leftovers recovery
252+ SpA Choice Specs Probopass Power Gem vs. 4 HP / 0 SpD Talonflame: 808-952 (271.1 - 319.4%) -- guaranteed OHKO
252+ SpA Choice Specs Probopass Earth Power vs. 0 HP / 4 SpD Mega Lucario: 298-352 (106 - 125.2%) -- guaranteed OHKO
252+ SpA Choice Specs Probopass Volt Switch vs. 252 HP / 4 SpD Azumarill: 210-248 (51.9 - 61.3%) -- guaranteed 2HKO
252+ SpA Choice Specs Probopass Dazzling Gleam vs. 4 HP / 0 SpD Garchomp: 228-270 (63.6 - 75.4%) -- guaranteed 2HKO
252+ SpA Analytic Porygon2 Tri Attack vs. 252 HP / 252+ SpD Florges: 85-102 (23.6 - 28.3%) -- possible 5HKO after Leftovers recovery
252+ SpA Analytic Porygon2 Thunderbolt vs. 4 HP / 0 SpD Talonflame: 328-386 (110 - 129.5%) -- guaranteed OHKO
252+ SpA Analytic Porygon2 Thunderbolt vs. 0 HP / 4 SpD Mega Lucario: 161-190 (57.2 - 67.6%) -- guaranteed 2HKO
252+ SpA Porygon2 Thunderbolt vs. 252 HP / 4 SpD Azumarill: 224-264 (55.4 - 65.3%) -- guaranteed 2HKO
252+ SpA Analytic Porygon2 Ice Beam vs. 4 HP / 0 SpD Garchomp: 552-652 (154.1 - 182.1%) -- guaranteed OHKO
You might want to note that a lot of these pokemon might kill whatever their facing before being killed themselves, particularly Mega Luke and Garchomp. In Luke's case, Sturdy Specs Probopass would probably be the only one of these that could counter, but if it already has some sort of offensive drop, he could be taken down by any of them. Garchomp would be more likely to be taken down by a Porygon2, since that's the only thing it can't Earthquake into oblivion, although the other two could potentially take him if they're holding Air Balloons and he's Earthquaking with a Choice item. Sand Force Probopass would need to watch out for Azumarill too, since Waterfall is an OHKO for it. Florges could be a problem for any of them, but Magnezone would be able to hit her hardest. Talonflame really is only a major problem for Magnezone here, thanks to weakness to Flare Blitz, and the only thing it could survive would be a T-Bolt from Porygon if it Roosts, and chances are slim it could Roost more times than you could T-Bolt (not to mention it's still have a net HP loss regardless).