You will require
2,400,000 EXP to reach the rank of 'Grand Master', which unlocks at
Level 126. This will take an extremely long time to reach but I do have some tips to help make this go quicker.
Firstly, I recommend playing through the careers first. There are several achievements relating to the career mode so you might as well play through those first if you are going for a completion. Once you have completed the careers you will need to find a way to farm EXP.
There are 2 main ways I would recommend to farm EXP:
1) Playing the Royal Rumble challenge on easy is a good way to earn EXP. You can clear the table in around 1 min to 1min 30 and usually get a good 500-800 EXP.
2) The second method I've tried is just by playing local 2 player games and getting player 2 to illegally pot the black. Games last about 25-30 seconds and you will get about 200-450 EXP a game. I think this method is fractionally faster overall but it is extremely tedious to do for long periods of time :/
I have included a video of the second boosting method to show you how it works in practice. As you can see it's fairly monotonous but it's quite quick to go through the games when you get into a routine.
I believe the second method to be slightly faster, but you may wish to use a combination of both just for a bit of variety. I personally took over 240 hours to get this but I think if you just focus on boosting methods you could get this in around
120 hours.
Please let me know if you have any questions or comments, good luck!