For Hypno, I feel it might be better to build on his existing strengths because with his mediocre stats across the board barring SpD, we can't really create new ones. Why not give Hypno a boost in defenses, making it into an excellent wall ? With even 20 in HP and 40 in each defensive stat, Hypno has amazing bulk with 105/110/155, which is tough to break through.
Alternatively, looking at the image for Hypno, we could give him Fur Coat:
This would patch up his mediocre defense and allow us to heavily invest in HP + SpD. I know most megas have the same HP, but in a case like Hypno's, a change by 20 is necessary.
As for typing, why not make him Psychic/Fairy? That would render his typing better, as he'd lose weaknesses to the Dark-type and the Bug-type in exchange for a Poison neutrality and a weakness to Steel types.