Adult Groot
As everyone expected, Baby Groot stole the show whenever he appeared onscreen. It’s no wonder that James Gunn decided to use this version of the hero, besides the timeframe (it rhymes with merchandise). However, the post-credits scenes revealed Groot as a teenager, which led Star Lord to realize what Yondu went through when he was in his teens. Given the MCU timeline (four years will pass between Guardians of the Galaxy: Vol. 2 and Infinity War), can we assume that the adolescent Groot was seen as the team headed to the Milky Way and Earth?
We can assume that.
We can also say that by the time they reach Earth, Groot will be a young adult with fully restored powers. So he’ll be an actual enemy for Thanos, whatever he might throw at the Avengers.
