all those mons got prio moves that have a chance to ohko so you cant rk/trap save those mons with it 252+ Atk Choice Band Metagross Bullet Punch vs. 0 HP / 4 Def Dugtrio: 190-225 (90 - 106.6%) -- 81.3% chance to OHKO after Stealth Rock
252+ Atk Life Orb Arcanine Extreme Speed vs. 0 HP / 4 Def Dugtrio: 191-225 (90.5 - 106.6%) -- 81.3% chance to OHKO after Stealth Rock
252+ Atk Black Glasses Bisharp Sucker Punch vs. 0 HP / 4 Def Dugtrio: 253-298 (119.9 - 141.2%) -- guaranteed OHKO
252+ Atk Empoleon Aqua Jet vs. 0 HP / 4 Def Dugtrio: 188-224 (89 - 106.1%) -- 81.3% chance to OHKO after Stealth Rock (sd set is used )