Perhaps not. But I'm not curious enough to take the time to check.

Is this Gastly/Haunter/Gengar?


Behind my gate,
I lie in wait;
The "gate" would be the portal between this world and the afterlife. These three Pokemon are ghosts, so they are no longer of this world, but not of the next, either. They are at the gate.

I stay up late
All three Pokemon can get Night Shade.

So I may sate
My hunger. Fate
They also learn the Hypnosis/Dream Eater combo to "sate their hunger." Also, those who don't switch quickly after Destiny Bond is used are fated to faint.

I would equate
To those I ate
Behind my gate!
Again, I reiterate the previous reasons for eating (Hypnosis/Dream Eater) and the gate (the barrier between this world and the next).