One of the reasons Aegislash was banned to ubers was that it made several offensive pokemon run sub-optimal coverage moves in order to be viable in OU. Examples include Earthquake Tyranitar, Terrakion and Heracross and Shadow Ball Gardevoir.

What if Gen VII introduces a pokemon that is solid OU material (and not broken) but it happens to have a combination of type, ability and movepool that forces the metagame to run specific coverage moves?

For example a Normal/Ghost type would force Gengar to run Dark Pulse, a move it has no reason whatsoever to run right now.

Can you come up with the most disrupting type/movepool/ability combo that forces the metagame to adapt?