Great Sage told me to put this here. This is a proposed change to the Steel Killer (Substitute) set for Magnezone:
http://www.smogon.com/dp/pokemon/magnezone
Magnezone @ Life Orb
Timid nature, 40 HP / 252 SpAtk / 216 Speed
-Substitute
-Thunderbolt
-Explosion
-Hidden Power Ice / Hidden Power Grass
The main change is running Life Orb over Leftovers. Why? First, Magnezone can achieve numerous significant OHKO's and 2HKO's with Life Orb which it cannot with Leftovers. Secondly, the lack of leftovers will in most circumstances not have an adverse affect on Magnezone's ability to do its job, due to its extremely common weaknesses to Fire, Ground and Fighting which make it unlikely Magnezone will want to stay in unless behind a Substitute. Magnezone's best opportunity for doing damage is usually after trapping a Steel, such as Scizor or Jirachi, most of which it can kill with a Substitute up and therefore has a great opportunity to damage the switch in. Lacking Leftovers does not negatively affect Magnezone's ability to beat any Steels which it can KO with Leftovers, or to do so with a Substitute remaining. Since Magnezone runs Explosion anyway, and can often have limited use after any relevant Steel types have been eliminated, I see no reason to provide it with recovery over a significant power increase (which also benefits its defenses, allowing Magnezone to run 40 HP and Timid over 40Atk and Naive while still OHKOing Blissey with Explosion).
Some important marks Magnezone can achieve with Life Orb which are impossible with Leftovers:
- OHKO offensive Azelf, Infernape after SR.
- OHKO SporePunch Breloom, good chance to OHKO SubSeed Breloom after SR
- 2HKO standard Tank Bronzong and Dusknoir
- 2HKO every Shaymin or Celebi without Leftovers
- OHKO 252 HP Dragonite with HP Ice.
- OHKO Gengar (98.1 - 116.1 % so guaranteed with SR or SS)
- 2HKO all standard Heatran (barring SpDefensive and Torment Tran)
- 2HKO physically defensive Hippowdon (guaranteed with SR + Leftovers)
- 2HKO non bulky Jirachi
- OHKO SD Lucario after SR (TBolt does 96.4 - 113.5% so almost guaranteed)
- 2HKO Machamp factoring in Leftovers
I also changed the Hidden Power types according to my opinion on their utility. Hidden Power Fire only allows notable extra damage against Scizor and Forretress,(as well as Grass types which are hit just as hard by HP Ice) both of which will usually be easily beaten with LO Thunderbolt (Specially Defensive Forretress with Earthquake is an exception). HP Fire leaves you almost completely helpless against numerous switch ins such as Gliscor, Hippowdon, Swampert, and to a lesser extent 252 HP Dragonite; it also invites Heatran to switch in, although the 2HKO provided by Life Orb on most Heatran variants mitigates this partially if Magnezone is behind a Substitute.
HP Grass and Ice are both better options in terms of coverage. HP Ice allows Magnezone to hurt Shaymin, Celebi, Breloom, Dragonite, Gliscor, Hippowdon, and so on, while leaving you unable to hurt Swampert bar Explosion (although Swampert will not usually switch in due to the prevalence of HP Grass). However I still believe HP Ice should be listed as the primary option.
Having tested this Magnezone extensively I can say that in the overwhelming majority of matches I've played Life Orb has been more useful than Leftovers.