Most 2 year olds will do anything to avoid having to lay still for a diaper change.
If your 2 year old is wiggling around or trying to run away from the diaper change try pinning him down on the floor and put one of your legs over his stomach to help hold him their.
If his dad is around then also have the dad help hold him down for the diaper change.
Before the diaper change remind him that it's time to change his diaper or if possible change the diaper on the couch or wherever he is.
I do this with my 2 year old son which makes changing his diapers much easier.
Also maybe put a video on a tablet or on your cell phone that he likes and allow him to watch those videos while you change his diaper.
That can distract him enough to change his diaper.
Then allow him to finish watching the video.
Or get him his own tablet that he can use to watch videos and tell him when he's good for his diaper change he can watch that tablet for awhile after you change his diaper.
If the diaper is just wet you can usually change the diaper standing up.