Tbh, I spent a lot of time working on my team, so I might as well share my thought process (mostly bcuz I love writing about my teams, I mean have you seen how many teams I write about in the General Thread?):
My first step to the team was Snow Warning Kyurem-W (which almost everyone ending up using at some point, but whatevs). However, I did something a little less standard by giving it Choice Specs, because it wanted consistent power to use since the BH metagame in general is heavily bulky.
Next I slapped on a Poison Heal Toxic Orb Giratina, mostly for drawing in status attacks with Rage Powder that would otherwise leave Kyurem-W crippled for more or less the entire match.
I got the idea of Prankster Transform Chansey after watching TOTEM attempt to use Belly Drum Meloetta-P in a Round 1 match. I figured having a way to take advantage of those sorts of sets would be useful. I also put Heal Pulse, Safeguard, and Thunder Wave (imo more reliable than Spore) on it for good measure.
Next I put Scrappy Meloetta-P on the team, mostly to provide Fake Out support.
I thought having an answer to opposing Trick Room would be a good idea, so I used Darmanitan-Z with no Speed EVs or IVs and a Life Orb for some extra power.
Still not satisfied with all my answers to Spore, I topped it all off with Safeguard Magic Bounce Lugia (I hate Spore in case you haven't noticed yet).
After a few test battles (like 2 or something) I decided Darm-Z was a weak point since it was so slow and tried out a Prankster Groudon which worked out pretty well.
With Giratina and Chansey for support, Lugia was more often that not just sitting there doing nothing in my games, so I decided to replace it with Arceus-Electric (disguised as Arceus-Flying) that attacked better with Blizzard while providing me with some Wide Guard support.
After a really close R2 battle with BlankZero it became apparent that my team was lacking offensive power outside of Kyu-W and Groudon (Meloetta-P was decent, but didn't do much to bulkier threats like Groudon and Giratina). I replaced Arceus with yet another Kyurem-W (the ability was Adaptability or something like that).
I then faced something like 5 defeats at the hand of Audiosurfer in the most torturous practice matches of my entire life (;-;) and decided to make a new team. I originally was trying some Eruption spam w/ Drought support when the idea hit me that with all the Kyu-W loose, some Steel-types would go a long way. I returned to my original team and put Escavalier in place of Meloetta-P and gave Giratina Trick Room while minimizing the speed of my Specs Kyu-W and Escavalier (basically making a TR mode). Chansey also had never managed to use Transform to much effect, so I decided to give Registeel a run in its place, with the same moveset except with Taunt > Transform and Follow Me > Thunder Wave (since TWave was redundant with Trick Room).
Things were probably fairly finished at this point, but with none of my Pokemon immune to Nature Power, Groudon wasn't so appealing to me. I decided to give Ho-oh a try, as Audiosurfer had demolished me with a Flying Gem Acrobatics Unburden Ho-oh in one of our battles (probably two of them tbh). I went with a Contrary variant though, since I liked the idea of V-create giving me some extra speed as well as bulk. I also gave it Fake Out and Wide Guard for some support. Finally, I decided to try Speed Boost Substitute Kyu-W over the Adaptability set I was trying (kudos to Mizuhime for this one, I practically stole her set except with Protect > Tail Glow and Spacial Rend > Dragon Pulse). And with that, I had my completed team that would take me through my Semifinals and Finals matches (already had done R1 and R2 at this point). The Team
Kyurem-White @ Choice Specs
Ability: Snow Warning
EVs: 252 HP / 252 Def / 252 SAtk / 252 SDef
IVs: 0 Atk / 0 Spd
- Spacial Rend
- Blue Flare
This was the only set I didn't change at all (bar minimizing speed which doesn't count imo). It did its job very efficiently. There isn't much to be said here. I never actually used Trick or Blue Flare (which was chosen over Heat Wave due to me being paranoid about Wide Guard), but having the possibility to was nice.
This set was basically the glue of the team, supporting me in a different way depending on what move it was using. Yes, it is completely Taunt weak, unfortunately. Sadly, I never got to use Heal Pulse, since Follow Me/Rage Powder were all over the place.
Basically the second halve of my "raw support" core, except it actually had an attacking move in the event that I needed one. Trick Room I never used, though the possibility of giving Kyu-W or Escavalier some really high speed was something I don't regret having in any way.
While it was added on mostly because Groudon didn't fit well on my team, Ho-oh proved itself incredibly valuable in every game I used it (which was only 2, but it is definitely awesome). I made sure that it could wall itself (Giratina also handles this set fairly well assuming I don't use Superpower too much for good measure) so that Imposter Blissey and such wouldn't be able to harm it, just in case I ran into one (which I didn't). Fake Out and Wide Guard both proved to be vital support options in my games, so I'm very glad I went with them.
The idea with this guy was to help me pick off opposing Kyu-W (which are incredibly common from my experience) as reliably as possible (Fire-type coverage from Kyu-W wasn't usually an issue as long as I had some Rage Powder support). I chose Gear Grind for Substitutes, which were pretty common. Wide Guard seemed like a good support move to have on two Pokemon so I could alternate between who used it, so I went with that for slot 3. Technician Bullet Punch was the idea behind using Technician, and it allowed me to pick off Kyu-W (who were obviously faster than me bar Trick Room).