It depends. If used by a STAB Pokemon, and is a crit, STAB makes venoshock effectively 90 BP.
Crits multiply the power by 1.5 so now it would be 135 BP. x 2 would be 270.
If no STAB, then it would be 180 BP. Of course, this isn't the most accurate, as type effectiveness alsso applies. Also if my be a little less than what it would actualy do. At stab counts as a modifier. Stats also greatly affect the outcome.