I this this is real muh-patterns-tier analysis, but I was taking a look at the types of the Megas and Primals, and which ones have been used the most.
Out of the final single/dual typings of the Megas:
>10 are Psychic-typed, 6 in ORAS
>9 are Dragon-typed, 6 in ORAS
>7 are Fighting-typed, 3 in ORAS
Lots on six:
>6 are Fire-typed, 3 in ORAS
>6 are Water-typed , 4 in ORAS
>6 are Steel-typed, 1 in ORAS
>6 are Flying-typed, 3 in ORAS
>6 are Dark-typed, 2 in ORAS
Then lower:
>5 are Ground-typed, 4 in ORAS
>5 are Fairy-typed, 3 in ORAS
>4 are Normal-typed, 3 in ORAS
>4 are Bug-typed, 1 in ORAS
And the lowest:
>3 are Grass-typed, 1 in ORAS
>3 are Rock-typed, 1 in ORAS
>3 are Poison-typed, 1 in ORAS
>3 are Ghost-typed, 1 in ORAS
>2 are Electric-typed, none in ORAS
>2 are Ice-typed, 1 in ORAS
So we've gotten one of every type in ORAS so far, except electric.
Mega Galvantula anyone?