Both of them introduced in Generation VI Pokemon games and does absolutely nothing. Both of them also shares this trait with Splash move that introduced from Generation I.
But not like Splash, both moves are event-exclusive move. Splash introduce because it have some related Magikarp that said it only can splashing around. People will remember Magikarp if we're talking about Splash and vice versa.
So, how about Celebrate and Hold Hands? Are they have related with some event (in Pokemon of course) or they're just... umm... useless moves?