MLB The Show 22

Enabling 'Dynamic Difficulty'
To turn on 'Dynamic' Difficulty, you will need to go to the gears icon on the top right of the home screen. Click it, then press the first option saying 'Settings'. The first section of settings you will see is for batting and baserunning, all you want to do then is scroll down to batting difficulty. Then press left on D-Pad until you see the difficulty turn to Dynamic.

Recommended Settings to Make This Easier
-Switch show Dynamic Difficulty Updates to 'Progress' in the General tab of the settings menu. You get to the general tab of the settings menu by pressing LB/RB in the settings. What this does is show you how far you are from the next dynamic difficulty on the bottom of the scorecard when you first come to bat. Alternatively, if you are pitching, it will show you your progress when the batter steps up to the plate to receive their first pitch. You'll see a blue bar, and you want to fill that blue bar fully to the right to achieve the next difficulty.
-You can set the batting controls to hwoever you wish.

The rest of the recommended settings are in 'Sliders'
-Dynamic Difficulty Sensitivity all the way to the RIGHT
-Human Contact, Power, Timing, Solid Hits all the way to the RIGHT.
-Human Foul Ball Frequency all the way to the LEFT.
-CPU Pitcher Control, Consistency and Strike Frequency all the way to the RIGHT. (Makes them throw more strikes, and strikes are easier to hit).
-CPU Starting and Releiver Stamina all the way to the LEFT
-Fielding Errors Infield and Outfield all the way to the RIGHT.
-Throwing Errors Infield and Outfield all the way to the RIGHT.
-Fielder Speed and Reaction all the way to the LEFT
-Fielder Arm Strength Infield and Outfield all the way to the LEFT.
-Baserunning Speed all the way to the RIGHT

With these settings, the CPU will be makin tons of errors, so you should be able to get hits easier.

Gameplay Setup
Go to Exhibition, and then I would suggest you pick the Visiting team to control because they bat first. Make your opponent a double A team. For yourself, pick one of the Legend Teams: Boomers, Groundbreakers, or Beasts. These teams are stacked with 99's, so it should make your job easier.

Gameplay
Just hit singles, doubles, triples, and HR's to fill the Dynamic Difficulty Bar.

Things to Note
-You will need to FINISH the exhibition game for your Dynamic Difficulty progress to carry over to future games. You will unlock the achievement as you hit the dificulty in real time, but if you haven't hit the difficulty yet and you reach the 9th inning, make sure you FINISH the game to get the remaining XP.
-I would suggest you bat as the visitng team because you can quickly restart the game if you go 3 and out (decreasing your Dynamic Difficulty meter). This way, you can at least explode starting from the 1st inning.
-If you achievement is bugged, you can uninstall and reinstall the game, then do all the gameplay shit to retry.