Yes, it can be KOed by the tapus and clefable but it has the edge in speed after clangorous soul. Leading with kommo-o doesn't allow entry hazards to be set up against it and also allows it to build up stat boosts before encountering tapus, which aren't often used to lead. Poison jab, drain punch and ice punch work well together on a physical kommo-o so yes, poison jab can be used better than close combat. I wouldn't use substitute with clangorous soul, which is necessary, because of the HP loss. Also, don't Garchomp and dragonite suffer this from ice attackers such as Garchomp and swampert.