Team A vs. Team D is a battle fought between Class 1-A heroes-in-training Ochaco Uraraka and Izuku Midoriya against Katsuki Bakugo and Tenya Iida during the Battle Trial Arc. The former pair (Team A) acts as the "hero team", whereas the latter pair (Team D) plays the part of the "villain team". The object of the battle is for the heroes to capture the payload being protected by the villains.
The battle begins when Katsuki ambushes Izuku soon after entering the building where the exercise is being held. Izuku swiftly dodges while moving Ochaco out of the way. Katsuki follows up with another attack, but Izuku is able to counter.
Izuku had taken notes on Katsuki in the same hero notebook the latter had burned and tossed out the window. Using his notes, Izuku was able to predict that Katsuki's opening move with be a right hook. After grabbing Katsuki's arm, Izuku slams him into the ground. He tells Katsuki that Deku is the name of a hero, no longer the defenseless boy from their childhood.
Katsuki is focused on attacking Izuku, so Ochaco uses the chance to get away and try to reach the payload. Katsuki attacks again, but Izuku is able to dodge using the capture tape given to him by All Might before the battle. Izuku quickly retreats to make a plan, severely irritating Katsuki. Meanwhile, Tenya tries his hardest to get into villainous character, making Ochaco laugh. Tenya notices Ochaco and informs her that he has already removed everything from the room other then the payload. Ochacho informs Izuku of the bad news, but he has enough to deal with as Katsuki finds him.
Katsuki makes comments on Izuku's Quirk and the notes Izuku has taken on his own Quirk. Katsuki reveals that the gauntlets on his hero costume store his nitro-sweat, and can release it all out once with a huge blast. Despite All Might's warning, Katsuki shoots it at Izuku. Izuku narrowly dodges the blast that destroys a large portion of the building. All Might warns Katsuki not to fire another blast or his team will lose automatically. Katsuki adjusts and moves into close quarters combat with Izuku.
Tenya and Ochaco both feel the explosion. Ochaco tries to use it as an opening to grab the weapon Tenya is protecting, but he uses his speed to keep it away from her. Meanwhile, Katsuki completely dominates Izuku in close combat. He uses his explosions to change trajectory in the air and blast Izuku from behind. Then he grabs onto Izuku's arm and slams him into the ground after using explosions from his free hand to build up momentum.
Katsuki once again demands that Izuku use his quirk, questioning whether Izuku feels he is too good for that now. This irritates Izuku, who expresses that he has always felt Katsuki is better, and that is why he wants to beat him. Filled with emotion, both fighters rush each other for a final clash.
Knowing he cannot defeat Katsuki at close range, Izuku uses one for all to smash the ceilings from every floor of the building. This smash creates enough debris for Ochaco to use on the floor above. She uses her Quirk to float debris and uses the improvised special move "Home Run Comet" to send them flying at Tenya. Distracted, Tenya is unable to stop Ochaco from grabbing the weapon and securing the victory for Team A.
Katsuki is shaken by the loss, and berates Izuku for having this plan all along. Izuku corrects him, saying that the only desperate plan he could come up with in time to defeat Katsuki. When the smoke clears, Katsuki is shocked to see that he has severely injured Izuku. Izuku is taken to the nurses office. Katsuki begins to hyperventilate over the thought of losing to Izuku, but All MIght comforts him and brings him and the others back to the viewing room. All Might and the class are impressed with Izuku and Uraraka, but give the most credit to Tenya's performance.