If you use my spread, see above, you can outspeed Starmie and kill with drill peck, even with a jolly nature:
Showing both offensive and bulky sets in their respective order:
+6 252+ Atk (custom) Drill Peck vs. 0 HP / 0 Def Starmie: 358-423 (137.16 - 162.06%) -- guaranteed OHKO
+6 252+ Atk...