I still need another QC check for this one.
And my Blissey was approved so I'll pick
Houndoom and
Mega Houndoom as my next pokemon.
+ 5 Speed
+ 5 HP (not necessary)
+ 5 SpA (its the weakest of all special sweeper megas)
+ Sludge Wave (it learns Sludge Bomb, this is just a little more powerful... you can remove this if you want)
Mega Houndoom gets Competitive instead of Solar Power.
It wasn't used much because the best sun setter was another mega but it now has its own niche. And considering the amount of Fairy types–and the fairy/water types that were just introduced, it deserves this.