Reed Richards along with the other members of the Fantastic Four is set to hit Marvel Rivals later this week, on the 10th of January. As shown in his new trailer, Richards AKA Mr. Fantastic will be a Duelist - the term for Marvel Rivals' damage dealers.
Richards attacks come from his stretchiness, allowing him to whip his enemies with his fists from great range. He can also wrap up enemies with his right click, slinging them into one another for a good bit of double damage.
His left-shift ability turns him into a bigger version of himself, allowing him to reflect projectiles, including ultimate abilities like Iron Man's maximum pulse. You may notice in the trailer Richards has a meter below his crosshair. That, when full, lets him have his own Hulk-out moment, where he once more grows in size and deals extra damage as well as gaining a load of temporary health. His E supports this, allowing him to charge straight into the thick of the fighting.
Finally, Richards' ultimate ability sends him flying up in the air to slam down with over-sized fists. It's a bit like Winter Soldier's ult except it seems to allow for multiple strikes right off the bat, without needing to kill someone in between.