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 second section of settings you will see is for pitching. You can get to this second section by pressing 'RB'. All you want to do then is scroll down to pitching 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 pitching controls to however you wish.

The rest of the recommended settings are in 'Sliders'
-Dynamic Difficulty Sensitivity all the way to the RIGHT
-Human Starter Stamina all the way to the RIGHT.
-Human Pitcher Control and Consistency all the way to the RIGHT.
-CPU Contact, Power, Timing, Foul Frequency, and Solid Hits all the way to the LEFT.
-Fielding Errors Infield and Outfield all the way to the LEFT.
-Throwing Errors Infield and Outfield all the way to the LEFT.
-Fielder Speed and Reaction all the way to the RIGHT
-Fielder Arm Strength Infield and Outfield all the way to the RIGHT.
-Baserunning Speed all the way to the LEFT
-Fastball Speed all the way to the RIGHT

With these settings, the CPU should be dogshit while your entire team is on roids

Gameplay Setup
Go to Exhibition, and then I would suggest you pick the Home team to control because they pitch 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 make sure you don't give up hits. Strikeouts make your Dynamic Difficulty Bar the most, so try to get those. Even in the Minor -> Rookie difficulty, you should still be able to paint the corners with fastballs for strikeouts. .

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 pitch as the home team because you can quickly restart the game if you find yourself getting shit on while pitching.
-If you achievement is bugged, you can uninstall and reinstall the game, then do all the gameplay shit to retry.