At Kearney, Oliver Wyman and Roland Berger, you can definitely apply for multiple regions simultaneously (you do not need to create a different account with another email address for that). You need to submit the applications separately, though.
However, in case two or more offices invite you for interviews, you need to decide for one. In case you are rejected after an interview in the office you chose, you would need to wait 1-2 years until you can re-apply, globally.
I don't know about Deloitte and Simon Kucher, since I haven't applied there.