To easily acquire the cumulative achievements such has "Hit 100 home runs with your User Profile", all you need to do is play against a friend or another controller.

Hit all the home runs you want, steal all the bases you want, or strike out all the batters you want. After a while, you should get the achievements.

However, this does not work with single-game achievements such as "Strike out 15 batters in a game" or "Strike 'em out, Throw 'em out". This only works for those cumulative achievements.