It's all about the entrances, at a guess the opponents gaining more exp have a bigger number of entrances?
Other ways to gain exp to have 3 taunts/3 finishers/3 trademarks, the more they hit the more exp you get.
IMO - Use most of the money you spend training moves into entrances.
I have close to 100 entrances and usually expect 8-10 exp per match.