Groudon @ Choice Band
Trait: Prankster
Adamant Nature
- Trick
- Nature Power
- Head Smash / Stone Edge
- Spore / Heart Swap / Recover
This is an incredibly underrated set that I'm surprised no one really uses. Priority Earthquake backed by base 150 Attack plus the boost from CB hits like an absolute truck - since the most common set by far is the standard Heart Swap set, no one expects Groudon to be able to hit so hard. Also, considering how the only common Ground immunity/resistance in BH is Lugia, it is very difficult for your opponent to safely switch into. Head Smash appropriately deals with it, though Stone Miss could be used if you're too much of a wuss to deal with the recoil. Groudon can easily revenge kill most of the metagame with this set, and get an easy clean up sweep in the late game with some hazards down.
Trick is another interesting quality about this set. In a metagame full of super-bulky Pokemon, Groudon can cripple all of the common tanks with Trick. No one ever sees this coming, considering how rare choice items are in BH. This can completely mess up your opponent's game plans. Oh, and Trick has priority too thanks to Prankster.
The last moveslot is the least important, though there's a few things you could run. I prefer Spore as it's amazing with priority as long as you watch out for Magic Bounce users. Heart Swap could be used to steal Attack boosts though, and Recover allows Groudon to stick around longer to tank things once it Tricked its CB. SD is another option, though I personally don't like boosting sweepers that don't utilise Substitute or Illusion as Imposter Chansey will fuck you otherwise.
Addressing Shedinja - it is totally dependent on team support to be usable. It incredibly easy to deal with due to all forms of passive damage OHKOing it. However, I do disagree with your comparison between Electivire and Shedinja. Electivire is merely a bad Pokemon that brings little to the table. Shedinja is essentially the epitome of high-risk, high-reward. If you can somehow remove all passive damage from play,
nothing can put you into a checkmate position as well as Shedinja can. In fact, the threat of it is why all teams have to run some form of passive damage in order to be viable.