Back to Magby, then.
Dratini @ Eviolite
Level: 5
Ability: Shed Skin
EVs: 108 Hp / 164 Atk / 76 Def / 36 SpD / 116 Spe
- Fire Blast
- Outrage
- Extreme Speed
- Iron Tail
Edit now with calcs: 236 Atk Life Orb Magby Fire Punch vs. 108 HP / 76 Def Eviolite Dratini: 4-6 (18.1 - 27.2%) -- 1.9% chance to 4HKO
(4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6)
236 Atk Life Orb Magby Mach Punch vs. 108 HP / 76 Def Eviolite Dratini: 5-6 (22.7 - 27.2%) -- 2.2% chance to 4HKO
(5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6)
236 Atk Life Orb Magby Thunder Punch vs. 108 HP / 76 Def Eviolite Dratini: 3-4 (13.6 - 18.1%) -- possible 6HKO
(3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4)
164+ Atk Dratini Outrage vs. 0 HP / 0 Def Magby: 21-25 (100 - 119%) -- guaranteed OHKO
(21, 21, 21, 21, 22, 22, 22, 22, 22, 22, 24, 24, 24, 24, 24, 25)
164+ Atk Dratini Extreme Speed vs. 0 HP / 0 Def Magby: 10-12 (47.6 - 57.1%) -- 80.9% chance to 2HKO
(10, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 11, 12)
Dratini ko's Magby with Outrage regardless of the latter's choice, and snipes it with espeed if it goes for Belly Drum. I just made it bulky because why not tbh.