Time for me to suggest what I think we've all been waiting for:
Passive damage weakness – SR, sandstorm, spikes, even U-turn or Pursuit, whatever it might be
- Weak to SR, susceptible to Sandstorm (though yes immune to hail whatever) and Spikes/Tspikes provided we don't give it levitate.
Good overall STAB combo – that means it should have both a wide coverage over the OU metagame and STAB that cannot realistically be spammed endlessly for maximum impact – That means no dragons (oh fine if you want)
- Obviously... Boltbeam. That being said neither type is truly spammable. There are plenty of electric resists and ice resists in OU for this to not simply be a choiced monster. However, obviously this will make set-up sets dangerous if we allow them.
Lots of weaknesses and resistances – It should be a risk to switch in, but that doesn't mean it should be impossible to do so
- Weak to Rock/Fire/Fighting/Ground (provided no levitate), resists Electric/Ice/Flying. This provides the interesting scenario that CAP4s safest switchin in OU may be CAP4, depending on spread/movepool.
STAB on notable risky moves – eg. Sucker Punch, Focus Punch, anything with a negative effect in essence (though I don't really like Sucker Punch but whatever)
- Nothing notable here, though I suppose like Thunder and Blizzard if a TTar switches in?
You know you want to make a Boltbeam CAP. You know you do.