The War Devil, Yoru, had a unique fight against Denji in Chainsaw Man Part 2. Denji used a non-traditional way to beat the War Devil because he didn’t have to rely on being stronger or giving a big speech to defeat him. He used the act of consuming devils as a weapon against Yoru. By consuming devils, he removed the existence of a devil from reality and mentally broke down the War Devil defeat.
That Guy's plan was insane. The way to make Yoru give in is by making it seem so bad that she needed to submit, or to scare her out of the idea of eternal war. Some effects were immediate and catastrophic, while others were slower, with some being more severe than others. Below is a complete listing of all the devils Denji consumed during this crazy fight in Chainsaw Man Part 2.
Devil Denji Ate During His Fight Against Yoru in Chainsaw Man Part 2
1. The Moray Eel Devil

In Chainsaw Man 2 Part 2, Denji’s first strike emotionally against Yoru was more about psychological manipulation than simply removing an essential idea from the equation. He used the Moray Eel Devil as a way to wage war on Yoru’s mind rather than destroy her belief system. To do this, Denji captured a bunch of Yoru’s devil friends and wore them as heads mounted on his body in the style of some crazy protective gear.
One of those creatures was Moray Eel Devil. Yoru really loved this thing, but while attacking Denji, she accidentally shot it. Denji took advantage of this and ate it right in front of her, and said something about how it tasted and made her feel bad about losing it. This directly led to her feeling broken inside.
She thought she was a brave, noble fighter; someone who does what's right at all times. But Denji made her learn that part of being a strong fighter means suffering losses. He made her realize that “the less you have of something (friends), the more painful your loss.” So basically, he said the fewer friends you have, the worse the pain is.
2. The Leg Devil

The Leg Devil was the deadliest weapon Denji could use when fighting. He ate the Leg Devil, so in Chainsaw Man Part 2, "legs" stopped existing. Birds fell off wires and couldn't land, pigs just fell on the ground, and people crawled everywhere with no legs.
Yoru in Chainsaw Man Part 2 found out how it felt to be erased when she got to the rooftop of Fourth East High School, and her legs gave out and leaving the War Devil unable to continue standing at a crucial moment.
The War Devil was given to Yoru by the Death Devil, who thought that Denji was working with the Death Devil's plans when really Denji was using the Death Devil against Yoru.
3. The Teeth Devil

When Denji immobilized Yoru using The Leg Devil in Chainsaw Man Part 2, he decided to take it up a notch by consuming The Teeth Devil. Just as he destroyed Yoru's weapon at a critical moment, she noticed a motorcycle and tried to transform it into a weapon using her War Devil abilities.
Unfortunately for Yoru, she didn’t have teeth and was unable to clearly articulate the transformation command. Instead, her speech became so garbled and unclear that she ended up with a chainsaw motorcycle that was terrifyingly uncontrollable. Her inability to clearly communicate what she needed left her with a chainsaw motorcycle that was only vaguely useful and amounted to being something she had to struggle to control.
Denji understands that every devil he eats is there to help him emotionally destroy Yoru, so he doesn't just eat 'whatever'; instead, he targets those devils that specifically target weaknesses in Yoru that will emotionally wear her down to the point of desperation.
Denji fought Yoru to redefine how we battle creatures like devils in Chainsaw Man Part 2. He didn't use superhuman strength or some other superpower to defeat her. The way the Moray Eel Devil defeated Yoru was by breaking her loyalty and trust in her friends. The Leg Devil defeated Yoru by pinning her down at exactly the right time. Finally, the Teeth Devil took Yoru's ability to continue to fight by stealing her voice and taking away her weapons.