Chansey and Blissey are those pokemon that everyone hates, but always avoid getting banned. If either or both of them got a mega evolution, how would you handle it (besides “don’t”)? For me it would be to crank up Blissey’s special attack and special defense with a little sliver of extra defense and make it Normal/Fairy, and I imagine that would be gamefreak’s mindset, which may be enough of a drastic powerup to push it into ubers, but you usually have different approaches to these things.

Funnily enough, I’m kind of okay with the idea of Mega Blissey being a thing, because at the moment we have this weird situation where Blissey is actually overshadowed by Eviolite Chansey, because Blissey’s main advantages over Chansey are greater special attack (who cares?) and Leftovers (meh, they have Softboiled).  That… brings up an interesting point.  Evolving into Blissey doesn’t actually make Chansey significantly better at her core role: her HP and defence only increase by minuscule amounts, and Chansey is already so good at special defence that Blissey’s extra points aren’t a huge deal (besides, Eviolite).  The real difference is that Blissey can actually use attacks.  So… if we’re doing a Mega Blissey, why not embrace that?  Put most of her mega evolution bonus points into special attack and speed.  Either leave her other stats as-is or only give token increases, maybe even cut her special defence a bit (there’s precedent for that; Mega Garchomp is slower than regular Garchomp).  Looking at something like [255/15/15/135/120/100].  Do some kind of vaguely seraphic design, lots of feathers and too many wings.  Add some gold to the colour scheme.  Make Serene Grace her sole ability, or even make a jacked-up version that triples the odds of weird stuff happening, just for fun (Thunder with 90% paralysis chance FTW!) – if that sounds like too much, remember that Blissey has no good special STAB; even if we go Normal/Fairy she’s only got Dazzling Gleam, which doesn’t synergise with Serene Grace (EDIT: correction; Alpha Sapphire and Omega Ruby have a move tutor for Hyper Voice – still, that doesn’t work with Serene Grace either).  If there is even a slight chance of a weird-ass [Gravity – Blizzard – Thunder – Fire Blast] set becoming a thing, I’ll be happy.