well sub>earth power could likely remedy revenge-killing issues, and it really wouldn't be missed all that much due to the lack of steels i the tier (in theory, of course, i'd have to do some testing).
i'm still in the position that i think that though shelmet is somewhat unimpressive in certain aspects, he's by no means a "bad pokemon". more so, i could usually keep him in play and not set-up-baity throughout the majority of a match. pokes like quag turned most issues regarding shelmet's set-up-baitiness down a peg (the only poke that could really set up adequately between the two is subcm serp, in my past experiences). plus shelmet prevents cb sawk and stuff from just powering through quag, which is always just a pain. i was just using this set for some time:
Shelmet (M) @ Eviolite
Trait: Hydration
EVs: 252 HP / 228 Def / 28 SAtk
Bold Nature (+Def, -Atk)
- Spikes
- Recover
- Bug Buzz
- Yawn / Body Slam / Toxic
i'm still in the position that i think that though shelmet is somewhat unimpressive in certain aspects, he's by no means a "bad pokemon". more so, i could usually keep him in play and not set-up-baity throughout the majority of a match. pokes like quag turned most issues regarding shelmet's set-up-baitiness down a peg (the only poke that could really set up adequately between the two is subcm serp, in my past experiences). plus shelmet prevents cb sawk and stuff from just powering through quag, which is always just a pain. i was just using this set for some time:

Shelmet (M) @ Eviolite
Trait: Hydration
EVs: 252 HP / 228 Def / 28 SAtk
Bold Nature (+Def, -Atk)
- Spikes
- Recover
- Bug Buzz
- Yawn / Body Slam / Toxic