... However, the ability is recalculated on certain events, such as evolution, so the Pokemon may have a different ability than originally intended. This is particularly of concern to Togepi, whose ability MAY change upon evolution to Togekiss to the unpopular Hustle instead of keeping its rare and incredibly useful Serene Grace ability. Unfortunately, without access to Togepi's PID, there is no way to predict whether or not the ability will change.
This says it may change to Hustle upon evolution, nothing about Togepi having Hustle and gaining Serene Grace when it evolves, so i'm gonna say it has Serene Grace.