Izuku Midoriya & Ochaco Uraraka vs. Katsuki Bakugo & Tenya Ida

Izuku Midoriya & Ochaco Uraraka vs. Katsuki Bakugo & Tenya Ida also known as Deku vs. Kacchan is a battle fought between U.A. Students Izuku Midoriya and Ochaco Uraraka (Team A) against Katsuki Bakugo and Tenya Ida (Team D) during the Battle Trial.

Prologue
All Might uses Class 1-A's first Foundational Hero Studies session for combat training. The students change into their hero costumes and meet him at Ground Beta. There he explains that he is moving the students two steps ahead of the urban battles they participated in during the Entrance Exams by pairing them up for indoor battles.

All Might explains the situation is as follows: the villains are hiding a payload inside the building and the heroes must secure it or defeat the villains within a time limit. The villains are granted the victory if they successfully protect the payload or capture the heroes.

The students are paired up based on chance by drawing lots. Izuku and Ochaco end up together on Team A. While Katsuki and Tenya are paired on Team D. Izuku is nervous about being paired up with a girl like Ochaco and hopes to make a good impression on her. All Might selects the first two teams to fight at random, and it ends up being Team A as the heroes with Team D as the villains.

Izuku glances over at Katsuki and fearfully looks away once he notices Katsuki is scowling back. Shortly after, Izuku finds his resolve and looks Katsuki back in the eyes, angering the latter. Team D is instructed to go inside the replica building. There, Tenya and Katsuki discuss Izuku's quirk. Tenya questions why Katsuki is so angry with Izuku but gets no reply. Katsuki silently prepares himself to fight against his former friend.

Meanwhile, Ochaco notices Izuku sweating through his costume. Izuku nervously explains that Katsuki is extremely talented and his attributes are superior to Izuku's own. Izuku goes on to state that he must improve and will win the Battle Trial. Ochaco asks if their battle is fated and Izuku apologizes for getting her wrapped up in his rivalry. She dismisses this and encourages their team to win.

Battle
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 expresses how he will injure Izuku to the point where the battle being stopped, just close, and follows up with another attack, but Izuku is able to counter. Grabbing Katsuki's arm, Izuku slams him into the ground.

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 would be a right hook. He firmly states to Katsuki that Deku is the name of a hero, no longer the defenseless boy from their childhood. Katsuki is enraged that Izuku, despite being scared, wants to fight him anyway, and vehemently says that’s why he hates him.

Since Katsuki is focused on attacking Izuku, Ochaco uses the chance to get away and try to reach the payload. Katsuki attacks again with a kick, but Izuku is able to block the attacking and attempts to use the capturing tape given to him by All Might before the battle, then Katsuki unleashed another right hook explosion, which Izuku successfully dodges. Izuku quickly retreats to make a plan, severely irritating Katsuki, who angrily expresses his belief that Izuku was tricking him for years by pretending to be weak.

While hiding from Katsuki, Izuku begins to formulate a strategy. Izuku can’t join Ochaco at the moment since Katsuki would follow behind him, and he can’t take to long dealing with Katsuki either since that would make Izuku's team run out of time. So Izuku settles on capturing Katsuki quickly before joining Ochaco against Tenya and claiming victory.

As Katsuki searches for Izuku, he thinks to himself as to how Izuku was just a bug he can squash, before remembering from their childhood how he fell into a river and Izuku tried to help him. Unfortunately, Katsuki took this as gesture as an insult, believing Izuku saw him as a weakling that needed help, and an infuriated Katsuki says that he much better than Izuku.

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 than the payload. Ochaco informs Izuku of the bad news, but he has enough to deal with as Katsuki finds him.

Katsuki taunts Izuku by asking him to use his power rather than hiding it. Then he brings up the notes Izuku has taken on his own Explosion quirk. Katsuki reveals that the gauntlets on his hero costume store his nitro-sweat, and can release it all at once with a huge blast. Despite All Might's warning, Katsuki shoots it at Izuku, saying it won’t hit Izuku as long as he dodges. Izuku narrowly dodges the blast that destroys a large portion of the building. Katsuki walks over to Izuku telling him how his gauntlet can release release bigger explosions the more nitro-sweat he stores in them. Smiling sinisterly, Katsuki claims Izuku will never beat him, no matter what power Izuku has. All Might warns Katsuki not to fire another blast or his team will lose automatically. Irritated, 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. 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, and calls Izuku a weakling.

Katsuki once again demands that Izuku use his quirk, questioning whether Izuku feels he is superior now that he is no longer quirkless. This irritates Izuku, who expresses that he has always felt Katsuki was superior, 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 the debris and uses the improvised special move "Comet Home Run" to send them flying at Tenya. Caught in the onslaught of rubble, Tenya is unable to stop Ochaco from grabbing the weapon and securing the victory for Team A.

Aftermath
Katsuki is shaken by the loss and berates Izuku for deceiving him. 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. In the monitoring room, the rest of Class 1-A also watches in horror of Izuku's injuries. All Might confirms the hero team's victory as Izuku slowly passes out from the pain.

Tenya checks on Ochaco's condition while Izuku is carried off to the nurse's office. Denki comments on the uncanny ending of the fight, noting that the heroes are injured while the villains are practically untouched. Katsuki is distraught over losing to Izuku, and begins to hyperventilate over the thought of losing to Izuku again if they fought all-out, but All Might comforts him and brings all three remaining participants back to the viewing room.

All Might asks Class 1-A to critique the battle and announces that Tenya is the MVP of the exercise. Tsuyu says that one of the heroes should be honored since they won but All Might refutes that notion. Momo explains that Tenya was the only one who adapted to his role and the situation. The others did not respect the spirit of the trial and made impractical decisions throughout the fighting.