Here is a Pokemon Revolution Online guide on how to teach Pikachu the move Surf.
All you need to do is go to the beach in Route 19 south of Fuchsia City. Look for Victor, you will have a battle and if you defeath him, he can teach your Pikachu Surf for a fee of 8,000. See the photo below.
Some said that this is only available if you had Pikachu as your starter Pokemon.
Now that we know that starter Pikachu can learn surf in Pokemon Revolution Online, does this make the electric Pokemon OP compared to other starter pokemon?