Sub-Zero and Johnny Cage will usually charge B2 when their opponent is in a vulnerable position.
Sub-Zero will freeze an opponent, charge B2, Cage will nutpunch an opponent, charge B2 and both usually cancel into pressure.
Ermacs does not have a special that leaves an opponent grounded and incapacitated for X amount of time, so it is a little more tricky to use it in a pressure game. Imho, it is best used at a distance where B2's forward cancel brings you within grab range / where 3 - 1 - 2 or f4 hit.
As
Metzos mentioned, the set-up is very situational and if incorporating B2 into your game, you really have to keep the opponent guessing on the follow-up. If you stick to the same routine, an opponent will read it and counter you every time.