I chose Riolu as a replacement, considering that he had no weakness to water and had proven himself reliable before.
As expected, the wild ducklett let out a water attack that inflicted little damage and mostly just got my pokémon wet.
My ally wound up his arm in a comical fashion and struck ducklett in a rapid succession of blows, dealing massive damage.
The enemy responded in kind with a more poewrful water attack, dealing more damage but not of any serious amount.
Riolu repeated the exact same motion as before and struck true, finishing off the wild pokémon.
I vaguely recalled the pokénav entry for this one to say something about it being slippery but my ally had no trouble with it, either this was a weaker version or my pokémon was just that good… probably both.