Poison

Anyone else find that people have a hard time understanding how poison works?

I was just battling someone with a Pikachu EX at 50 health. I had a full health Weezing in my active spot and the Pikachu was already poisoned. Both of us had two points.

The Pikachu could have been retreated for another fully health Pikachu or Zaptos but instead it hit my Weezing for 90 and I won on my next turn.