I recently saw a battle video that helped me come with this potential lineup for Double Battles:
- Hidden Ability (Truant)
- Focus Sash
- Any Pokémon with Heal Bell or a related attack
The idea is to lead with Durant and Shedinja, have Durant use Entrainment to pass its Trunt ability to an opponent, then have Shedinja use Mimic to learn Entrainment.
On turn two, switch out Durant for Spiritomb and have Shedinja use Entrainment on it to pass it Wonder Guard.
Should Spritomb be hit with Poison/Burn, the Heal Bell can fix it, and it can counterattack with its own status-inflicting moves.
So what dangers should this team look out for? Obviously if Shedinja is taken out before it can use Entrainment the whole thing falls apart (faster opponents, Rock Slide/Heat Wave combo...) but usually the risk of this happening can be predicted just by looking at the opponent's team on the preview.
Aside from that, I think the only real risk is the Heal Bell user being KO'd. Are there any other risks I haven't seen here?