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Well, Peck will KO no matter what item I take, so uhh.... Take the Prickly Rose (Grass type) because it has the funniest description. Also take this Amulet Coin because free money is nice.
Recap:
Marathon Shelmet strapped on a pair of Mad Scientist Goggles which zapped him out;
Rhea-Burmy was stuck with Scuba Flippers on her stem, enabling her to swim around by spinning like a top;
TW-Spheal's blubber all froze up after spending some extra time in the Refridgerator;
And Robin-Rufflet was whipped silly by Prickly Rose and Rosefied by the toxins.
Action 1: Burmy used Protect!
(+4 Priority) Burmy protected itself!
-7 energy
Rufflet used Peck!
RNG Roll (CRIT) [<=625 CRIT]: 9064/10000 (NO)
[4+3+(6-3)]*1.5 = 15 damage ~ -6 energy (Burmy)
-2 energy
Action 2: Rufflet used Peck!
RNG Roll (CRIT) [<=625 CRIT]: 3601/10000 (NO)
[4+3+(6-3)]*1.5 = 15 damage (Burmy) Burmy is KO'ed!
-6 energy
Post Round:
Burmy: -15 HP, -13 EN, KO'ed
Rufflet: -8 EN