In Story Trailer 1, Ultron and Sigma fuse to become one. They seem to have possession of the Space Infinity Stone and the Reality Infinity Stone. They seem to siege Asgard with a robot army. When Thor, the Avengers, and many Capcom heroes such as Chris Redfield, X, and Strider Hiryu, try to take back Asgard (called Xgard following invasion), Ultron-Sigma comes and fights them all, seemingly taking them all down effortlessly.
Ultron's apperance is the same from the one in the 2013 Marvel comic book storyline "Age of Ultron" (not the same story as the Avengers movie that borrowed the name).
He is a metallic android that has orange highlights around his body that also make the facial features on his head. He also has spikes on his fingertips which can be utilized for slashing opponents.
Ultron can fire lasers out of his eyes and also call in a giant laser from out of sight. He can summon a minion to the field to attack the opponent. He mainly uses his claws to attack and launch enemies.
His first Hyper Combo shoots two crossing lasers in front of him and can be done in the air.