What does it mean when a Pokemon has its energy drained?

Question

When you use a damaging health restoring move it says "The opposing Pokemon had its energy drained!"
What does it mean?

Answer 1

This phrase simply means that your opponent lost HP and you gained a portion of it. You literally "drained" their HP.

Here's a list of all the moves that result in the message;
"The opposing [Pokemon] had its energy drained!":
Absorb
Giga Drain
Mega Drain
Horn Leech
Drain Punch
Leech Seed
Leech Life
Dream Eater
Oblivion Wing
Draining Kiss
Parabolic Charge