[DISCUSSION] Best non-legendary user of Z-Celebrate/Happy Hour/Hold Hands?

[PerchPond]

I'm intrigued by the idea of getting a guaranteed Ancientpower-boost to all your stats in one turn,
but what Pokémon can pull it off best?

I'm not bothered about tiers really, nor if it's for doubles or singles, just individual Pokémon.

Obviously Rayquaza, Victini, Jirachi and Ho-Oh can use it really well with their sky-high base stats, so I don't care about them either.

Feel free to leave comments on what you think

Cheers