Notes on Mega Evolution

Assuming Megas are preserved:

-Gen 8: HP changes are now available.
-Gen 10: Multiple abilities are now available.
-Gen 12: Megas now have different stat boosts.
-Gen 14: Megas can now be retained and learn new moves.

Assuming Megas have successors:

-Gen 8: Mega successor retains the abilities, but increases the boost to 120.
-Gen 10: Mega successor has a variant range of 100-140. They have multiple new abilities.
-Gen 12: Mega successor has a variant range of 100-160. They all have the same ability.
-Gen 14: Mega successor has a variant range of 100-180. They have no abilities.