Shield (Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey)
From the Super Mario Wiki
Shield is a first officer command used by Morton in Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey. It is Morton's first command, the second being Thwomp Thump. It costs four CP to use. It is the first command used by a first officer to be learned in the game. When this command is activated, Morton will use himself to form a wall in front of Bowser Jr., preventing enemies from attacking him. Every time Bowser Jr. berates Morton (or encourages him, after reaching his point of maturity) for doing so, Morton will receive a boost in POW or DEF. After a while, Morton will return to his position, ending the command. The player can end the attack early by pressing . If Morton's HP reaches 0 while the command is still active, he will give in his "last gasp" by attacking an enemy before being ultimately defeated.
The Shield command is first learned when the level Koopaling Teamwork is played through for the first time. This level serves as a tutorial for the Shield command and an introduction for first officer commands.