Okay so I'm walking in yellow forest and I have 2000 watts looking for a fly/surfing pikachu, and NOTHING! I only got too !! sometimes, but never !!!
The pokemon in !! was had volt tackle if you need too know.
Does anyone have any tips of how to find it?

I was wondering about this too when i first used the yellow forest map. Anyways, you need to have over 10,000 steps recorded for when you actually try to look for the pikachu. Also when looking for them it has to do the exclamation mark thing 2-3 times(at te same time) in order for it to possibly be the pikachu you are looking for. It might also help if you look at the pokewalker guide on this site. Here's the link http://www.psypokes.com/hgss/pokewalker.php Hope that helps (:

Okay this just sucks! I had over 40000 steps and find a !!! and when I go into battle with it, it runs away! Then some hours later I find another !!! and guess what IT RUNS AWAY! I then took my anger out by killing the elite four in fire red for the first time ^_^

If I recall correctly, you only have like a two percent chance of encountering the surfing or flying pikachu. On top of that, they're VERY difficult to catch. Everyone has that same trouble. And if you're having problems with them running away, try evading less often.