When you select 
Character > Edit Properties in the Character Controls, the following Retarget Specific attributes are available on the HIKProperties tab in the Attribute Editor.
Determines whether the target character follows the movements of the source character exactly, matching the position of its joints in space, the length of its stride, and the extent of its movements, without taking differences in scale between the two characters into account.
When on, the solver calculates and compensates for the space between the target character and its source character. The target character still moves with the movement of the source character’s feet, but Maya makes adjustments to compensate for scale differences.
For example, when this property is on, retargeting a walking animation from a smaller character to a larger character makes the larger character place its feet in the same spots as the smaller character, appearing to take tiny steps.
When you set Action Space Comp Mode to User, Maya applies this value as a percentage to the size of all movements carried out by the source character when determining positions for the target character. The default is 100. Use the following as a guideline:
Sets whether the target character mirrors the movements of the source character.
When on, the target character mirrors the movements of the source character. The solver flips the position of each of the source character’s nodes along the X-axis in order to determine the desired position of the corresponding node of the target character. This effectively flips left and right: when the source character moves its left arm, the target character moves its right arm, and so on. When off, the target character does not mirror the movements of the source character.
By default, Auto mode adjusts the distance between your target character’s left and right ankles. The solver adds its value to the spacing between the source character’s left and right ankles in order to determine the spacing between the target character’s left and right ankles. When Off, no adjustment occurs. When set to User, you can enter a specific Feet Spacing value to adjust the ankles.
If the scale of your source and target characters differ, use this value to adjust the distance between the character’s foot and the floor. You may also have to adjust this option if your character’s feet are large, or if your character has special height requirements (for example, shoes with high heels or boots).
The Reach attributes let you define the translation and rotation reach between the target character and the source character. See Adjust retargeting parameters.
Reach values can be set per effector for each body part listed, including the head, chest, elbows, wrists, hands, knees, ankles, and feet.
The Pull value of an effector determines the priority of that effector relative to the other effectors acting on the character. Setting a high Pull value makes the character appear to lean toward that effector with the rest of its body. Note that Pull applies only if the reach translation value on the effector is greater than 0.
The Pull effect is only apparent if the effector is beyond a certain distance from the body. For example, the pull effect on a wrist effector is only visible if the effector is so far from the body that straightening the arms doesn’t allow the wrist bone to reach the effector. If Pull is set to 100 in this case, the rest of the body leans so that the wrist reaches the effector.
The Stiffness value of an effector determines how strongly the effector maintains its original position, orientation, or angle when the pull of another effector affects it. Stiffness applies only if the reach rotation value on the effector is greater than 0.
