>>48078609Round 4:
I wrote up a huge script giving it to the Greninja and Aegislash team before realizing I forgot to factor in Intimidate. Safe to say, if the two teams know they're going to fight each other, Pelipper and Mawile will win more often than not due to Tailwind. Pelipper just barely lives a Specs Hydropump in the rain from Greninja, and with 216 speed EVs and a Jolly nature, it always outspeeds Aegislash for the Tailwind.
Turn 2 is Mega Mawile OHKO'ing Greninja, and Pelipper Scalding Aegislash, assuming Aegislash hasn't Shadow Sneaked on it twice and KO'd it. Either way, Turn 3 is a Mega-Mawile vs Aegislash stand off, in which case it comes down to King's Shield mind games. Assuming Mega-Mawile's user knows this and packs Swords Dance, it's a guaranteed Mawile victory, whereas Aegislash has a ~1/3 chance of winning otherwise through predictions.
Winner: Mega-Mawile and Pelipper