Just a few ideas I had. Some of these are pretty crazy, but hey, it shouldn't be easy getting stuff like Platinum God.
Schlieffen Plan: Faint at least 3 of the opponent's Pokemon within the first 10 turns. Stall for the next 40 without losing a single Pokemon on either side.
Hijack: Faint all six of your opponent's Pokemon with Ditto. Does not have to be done in succession (in other words, Ditto can transform more than once.)
Feeling Under the Weather: All of the opponent's Pokemon must faint due to weather-related damage (this CAN include Solar Power/Dry Skin in sunlight).
Who's That Pokemon?: Win a battle using a team with a Zoroark in it. Over the course of the battle, Zoroark must have impersonated every other Pokemon on your team at some point.
Explosive: All Pokemon on both teams must faint due to Explosion, either through the attack itself or its aftereffects. Although other attacks may be used, Explosion must be the cause of fainting.
Triplets: Win a battle using a team composed of two complete Legendary Trios.
The Very Best: Win a battle using one of Ash Ketchum's teams (this means Ash must have carried all six Pokemon AT THE SAME TIME at any point in the anime. This also means that Pikachu, by default, must be on the team.)
Where's the Mega?: Win a battle using a team comprised entirely of Pokemon capable of Mega Evolving. Every Pokemon must hold their respective Mega Stone.
123456: Nickname your Pokemon 1 through 6. They must appear in the battle in that order, and stay in until they faint (e.g. when 1 faints, 2 comes in. When 2 faints, 3 comes in.) Win the battle.
The Choice is Yours: Win a battle with a team entirely composed of Choice item holders. Trick/Switcheroo/Klutz is legal, provided the Pokemon enters the battle with a Choice item.
Struggle Bus: KO one of the opponent's Pokemon with Struggle.
Status-tician: Afflict every single Pokemon on the opponent's team with status at some point during a battle without having KO'd any.
