No reason.
#GamefreakLogic
Seriously there's nothing more to expect. It's an exact ditto of False Swipe.
However,this is not the first time Gamefreak has done so.
Like Growl and Play Nice, other than type differences, there is no difference at all. Same goes for Aromatherapy abd Heal Bell. The best example of this is in healing moves, like Soft-Boiled and Recover.
It also lets most people distinguish that this particular Celebi was obtained in the occasion of the opening of PokeBank. This might be the closest explaination.
EDIT: Heres some real reason I just found. Celebi doesn't get access to False Swipe. As of such, for whatever reason Gamefreak decided it should, but just decided that they want to change it's name (or they just forgot False Swipe indeed exists xD) .
Now this means that Celebi can be used to capture Pokemon more effectively. For players who:
- Don't have False Swipe
- Prefer Celebi as it cannot be statused (Heal Bell)
- Want Heal Block to stop healing
- Want a freely available catching Pokemon
- Think False Swipe is too mainstream
… Hold Back actually has some significance. Mostly because it fixes the fact that Celebi doesn't get False Swipe to become a good Pokemon capturer.
Hope I helped!
