What are the best course for a mechanical engineering graduate student to pursue in canada
He can pursue Mechanical Engineering if he completed his Bachelor.
Requirements For Mechanical Engineering.
All schools in Canada with a comprehensive engineering program offer degrees in mechanical engineering. Completion of high school is required for admission to most diploma and certificate programs in mechanical engineering, with the completion (and an average of at least 60%) of English, math, and physics.
Thanks,
Azim

After Mechanical you can go for number of different specialization like :
Designing
Automation
Industrial automation
CAD CAM engineering
Engineering Management
Manufacturing
Production
MBA
Aeronautical engineering
So it's up to your interest. Canadian Universities don't have niche programs but you can find three types of Masters there i.e MSC , MASC & MEngg . Once you go through the course contents of the Universities you will get to know what will be best for you .
Hope this may help you.
Good luck !!!
So opt any other course.