How did Iruka become chuunin?

[GiantShuriken]

Because of the 9 tails attack and it took out most of the ninja and they needed more ninja so he became one and they needed chunin to do missions and then he became a teacher.

Let's all give a round of applause to Iruka sensei xd

wow, that sounds like the most reasonable answer! It would explain why so many fodder guys who have never weaved a hand sign made it to chuunin.

 

[Icelerate]

You realize why the likes of Kakashi became a jounin at such an early age even though I believe some of the genins during the chunin exams were around his level or even stronger. The reason is simple, those were harsh times for Konoha and they needed more chunin and jounin since so many of them were dying in times of war. The standards to becoming chunin and jounin were rather low and the fire country was pumping lots of money to fund the recruitment of more ninjas to fight and protect the country at large during the times of war.

The reason the talented genins couldn't become chunin but noobs such as Iruka and Mizuki were allowed to become chunins is quite simple actually. Those genins were all very talented for their rank and level so the competition was very intense. There were times of peace so there were already a huge number of excess chunin and jounin ninjas in the Five Great Countries. Also bare in mind what Pain said, he basically states that the governments are pouring less money to fund the ninja system because there were no wars. This meant the competition between ninjas increased a lot.

Iruka, Mizuki and Ebisu had been promoted because of the lack of ninjas but the likes of Neji weren't because of the surplus of ninjas during those Chunin exam chapters.