Celebrities popping up in off-brand cameos is nothing new but it was still quite the surprise to see LeBron James hopping into MultiVersus.
LeBron James' release date in MultiVersus is July 26, 2022.
Now, in regards to the question of "how did this mashup happen", it's probably because LeBron starred in the Space Jam reboot where Looney Tunes characters formed a basketball team with him. Seeing how Bugs Bunny and Taz are already in the game, LeBron doesn't actually feel out of place any more than Batman or Finn the Human would.
His skillset will largely revolve around basketball and he does carry a ball around all the time. One of the moves literally has the legend dunk the ball on his opponent so it will be quite interesting to see the associated jargon as the community develops and people start shoutcasting the matches.
The new character's release date, and likely the time, will be at the same point as the game's launching of the free-to-play portion of the Early Access. Considering MultiVersus has already enjoyed over 50,000 concurrent users in the past week when only people who bought the optional packs had access to it, expect to see server issues, lag and queues when a massive influx of players happens at launch.
Oh and keep in mind that the concurrent player count we cited above is only for Steam. MultiVersus features crossplay with PlayStation and Xbox consoles across two generations so the actual player pool will be massive, meaning you won't have to wait long in the lobby to get a match.