
Toxicroak @ Life Orb
EVs: 4 HP, 252 ATT, 252 SPE
Nature: Adamant (+Att, -SpA)
- Swords Dance
- Cross Chop
- Ice Punch
- Sucker Punch
Straight from the Analysis - Immune to hydro pump, and Thunder (Starmie's most powerful move) only does 50.32 - 59.41%, not a 2hko after 1 turn of dry skin. (Assuming rain, as thunder is being used)
Suckerpunch in turn does 95.78 - 112.64%, 65% chance of a OHKO.
If Starmie Tricks on the switch, giving itself the life orb, Scarf croak Sucker Punch: 73.56 - 86.59%, its still a guaranteed 2hko. The only way for Starmie to win ON A ONE-ON-ONE BASIS is to stall out Sucker Punch with continuously tricking, Cross Chop is still a 3hko though, so its a risk.