It's true, he's a good villain! But...Ninja man is my favorite Kanto Gym Leader, so it was a bit of a shock.
I was just like (in Lavender Town) "Oh my gosh! It's Koga!" when he did the standing pose. But then Red's like "It's you from Mt. Moon!" so I thought "Oh, it's not Koga." Then he says "My name is Koga! I am a member of Team Rocket's elite!" and then I'm just like "OH MY HO-OH IT IS KOGA!! WHAT THE HECK?!"
Funny in hindsight, but man was I shocked!