Well as per my experience most of the top MiM schools require the GMAT. Also several schools have started accepting alternate exams such as
1)GRE
2)Tage Mage( French schools)
3) CAT (an Indian exam for MBA colleges- many MiM schools have started accepting it too)
4) Some German, English and french schools accept on the basis of your CGPA and maybe a qualifying English exam such as Toefl or IELTS
There have also been instances where really popular schools such as LBS have allowed students to apply without giving the GMAT, but this usually happens if the person has a proven ability in maths or if its a last minute application and there is no time to give the GMAT. I am sure other schools will also have provisions like this.
Apart from this a few schools, who i know for a fact accept students without the GMAT are Audencia Nantes, Grenoble. I am sure there are many others, just do some digging on the school's webpages.
Lastly, if you are serious about only applying to top schools, give the GMAT! Its worth the effort

You can check out
What is Masters In Management? for more info on the MiM degree and reviews on some top schools.
Hope the answer helped.