Fans of the MCU Guardians of the Galaxy movies may be remorseful about the game's lack of faithfulness to the movie adaptation. Luckily, there is an option in the 2014 film to change Groot's appearance to his Marvel Cinematic Universe look.
You can find the Guardians of the Galaxy (2014) Groot outfit during the Wrecked Mining Vessel level.
Once you have found the yellow infinity stone and completed the cutscene, turn right until you find a hole within the pink mess. If you walk into the area, you will find a room filled with yellow boxes. On the right side, there is a purple box that needs to be opened.
The Groot costume will then be available for you to equip onto Groot.
You can equip it by pausing the game and switching to Groot on the right. You can equip it by pressing triangle on PlayStation or Y on Xbox. Rocket muses about making a movie about his adventures and complains that he doesn't want to ride on a naked guy.