From MLB Power Pros Wiki

Intimidator is a blue ability that 'makes (opponents) nervous'. There are two separate abilities by the same name, a hitting ability and a pitching ability.

Hitting Intimidator

• Will drain more stamina per pitch from the pitcher during every plate appearance
• Lessens pitcher's control in the previous hitter's plate appearance

Pitching Intimidator

• Reduces batters' power
• When pitching in relief, shrinks batters' hitting cursors significantly