Flonkey, when Psyshock tosses the bomb at you, Fling it back to their side of the field. Then, once Leo has Sketched Pain Split, use Amnesia so he forgets how to Sketch it again. Finally, once Creeper has exploded, use Fire Blast on Leo.

Pingu, start with Hydro Pump on Psyshock. Follow that up by Protecting against the Pain Split ball. Finally, once Creeper has exploded and Flonkey has used Fire Blast, use Signal Beam on Leo. (If Leo has fainted at this point, direct the Signal Beam at Psyshock.)

Flonkey: Fling (Creeper) ~ Amnesia (Leo) ~ Fire Blast (Leo)
Pingu: Hydro Pump (Psyshock) ~ Protect ~ Signal Beam (Leo/Psyshock)