I would assume that if for instance in a doubles battle your Pokemon uses Bulldoze it couldn't become a critcal hit and increased damage for every Pokemon hit but for each Pokemon there is a chance its a crit .
If a Bulldoze crits 1 Pokemon, it has the normal 1/16(gens 1 through 6)chance to crit and the 1/24 chance to crit(since gen 7 and beyond currently).
As shown in this replay, my Barboach crit the Goodra, but it didn't crit the others. Since Earthquake, Bulldoze, etc have the same hitting all Pokemon effect, the answer is the same for the others. Thanks ManectricMadness for helping with the battle testing!