Hello, relatively new player here. I would like to know what I should keep in mind for EV'ing a defensive mon. I can do so for generally offensive and fast Pokemons as they use max speed and max attack of choice, but every time I see a defensive or bulky build, I am confused as to what the EV's are for. Is it to allow them to take hits from their common checks or are surprise sets which allow them 1 v 1 some usually problematic threats ?
For your first Question: specific EV spreads on bulkier teams allow to tank some certain hits or some players just want to speed-creep a Pokemon and put the rest into the specific HP and Defense-stats. As Example: Reuniclus speed creeped Haze Toxapex, to have a setup prior to Toxapex coming in and to dish out damage first on Toxapex, before Toxapex can make use of Haze to reset the status-boosts. But speed-creeps can only come so far, as at one point it'll be unnecessary as due to more invest in speed, more and more bulk gets lost. Another example is Melmetal currently with 16 speed EVs allowing it to outrun Toxapex by 2 points, you can go 12 if you want, as it still outpaces Toxapex by 1 point exactly.
Also, is running band on a Jolly Cinderace good as he bags too many KO's for me but loses the ability to switch moves (Life Orb) and being locked means I have to switch out many times, which can be problems if my hazard remover is gone.
To the second Question: Choice Band Cinderace can act as a nice and fun offensive pivot with U-turn, Pyro Ball, Gunk Shot and Zen Headbutt, but I think you should put a decent amount of entry hazard removal on your team, or support this Set very well, to make it work in the long run. Currently the Mainsets are either Heavy-Duty Boots-variants, or Life Orb-variants, HDBs to not be prone by hazards, as example on Hyper Offensive-teams, whereas Life Orb can dish out more damage if you decide to go for the power route. Both Sets, HDB and LO alike, can work well on Hyper Offensive-teams, HDB can also work outside of Hyper Offensive-teams, but while Choice Band is more niche, it can work well too, if you support this set well, with defoggers like Hydreigon or Mandibuzz, which have Roost to ensure the longevity while Defogging.
Final questions, is a suicide lead Gigalith good in OU right now ? I have been using him and he almost always does his job by setting up to rocks with sturdy and nabbing a surprise kill with priority explosion thanks to Custap Berry. But I'm still in the 1400's so I don't know what is the state of the players in that part of the ladder. (And I do keep a Bisharp to punish expected defoggers)
The build is :-
Gigalith @ Custap Berry
Ability: Sturdy
EVs: 252 HP / 4 Def / 252 SpD
Adamant Nature
- Stealth Rock
- Stone Edge
- Earthquake
- Explosion
To the third Question: That Set of Gigalith isn't bad at all in my opinion, and can net in some surprise KOes with sturdy + custap berry in combination, it can also run something like Smooth Rock or Leftovers, Smooth Rock to guarantee more turns from 5 to 8 for Excadrill or Dracozolt as these are great partners to it. Leftovers are for more longevity. But in overall this Gigalith-set is pretty good, but another great suicide-lead on HO is Lando-T as it can do the job pretty well too with Focus Sash, Stealth Rocks, Earthquake and Explosion. It can also run Rock Tomb or Stone Edge in case you want to hit flying-types without sacking Lando-T early off, if it isn't necessary. Gigalith however can be a great alternative, but on HO builds, I personally would use Lando-T as it doesn't damage its teampartners with sand-Stream, unless it is an offensive Sand-team, which I think Gigalith can excell pretty decent on.
I hope I was able to answer your Questions :)