Your most surprising moment in a pokemon game!

[Rai]

It would probably have to be the first time I encountered a shiny. I had no idea that shinies even existed so it was a shocker for me.

 

[Weavile05]

When I found a shiny Stantler on my Silver ROM (ultimate monotype challenge)
of course, I ran out of pokeballs. This was my first shiny EVER!

I got the game back for the stantler though by catching a Swinub (even though I can't use it since I was doing a Normal type run... oh well) First shiny ever caught.