Not just surf, earthquake too. I learn it the hard way during my double battles at the Battle Towers. If you are to use surf, I suppose it would be better if you use Surf and paired that Pokemon up with either a Leaf type or a Water type where it would do lesser damaged.
I paired my Golduck with Leafeon in double battles. Surf does hit Leafeon but Leafeon still regains its health due to Synthesis and Shell Bell.