What it requires:
An Espeon evolved at lvl 57 (due to it's high special attack) that is EV trained...
Some ghost pokemon with the move spite
Next you would use a single pp up on trump card (this is due to spite removing 4 pp)
Now for battle :
1. Get Espeon to use trump card as the very first move of the entire battle
2. Use spite on Espeon with your ghost pokemon
3. Wait for a particularly strong pokemon in the opponents pool
4. Use trump card on this pokemon and (maybe?) OHKO it.
Another thing to note here is that there should be other moves that are useful on both pokemon while waiting for the burst attack
just a thought if it somehow could be used...
if any questions feel free to ask... I know it's a burst attack... and it's for duo battles...¨
EDIT: Nonetheless for casual playing...
And the above strategy is similar to the Fake Out + Last Resort strategy that can be employed by Ambipom in singles. While it looks good on paper, it's absolutely horrible in practice because what if a Ghost Pokémon switches in and forces you to burn up Trump Card's last PP?