I recall once Genos's "creator" told him after some upgrade he "might be stronger than his friend now" (of course this is wrong). Also Genos was broken several times and he had to be repaired , in those situations it's hard to know if he was upgraded or not, but later he displays attacks and features he hasnt showed before. Perhaps the manga or the webcomic goes deeper into this, how many times is clearly shown Genos was upgraded in the One Punch Man story?
- Set 1 (Initial) - [Appears in chapters 5-6] This is the first set Genos appeared in the story with. Has not made a reappearance beyond his fight with Mosquito Girl.
- Set 2 (Emergency Replacement Arms) - [Appears in chapters 7-11, 15-16, 30-32, 35-37, 45, web chapter 57, and volume 8 and 10's extra chapters] I came to the conclusion that these arms were Genos' extra arms for emergency repairs as, after the House of Evolution's arc, he never has this set equipped for battle again (except for Boros' arc, when he was called over to attend the S class meeting from Bang's dojo). I assume that, whenever he has these arms equipped, his regular set of arms are being repaired or upgraded by Dr. Stench, or being set aside for later maintenance by Genos.
- Set 3 (Anti-Saitama tactical arm TYPE-00) - [Appears in chapter 17] The set of arms Dr. Stench created for Genos to compete against Saitama (expounded upon in the anime episode). The name of this set was written on the fist.
- Set 4 (Upgrade 1) - [Appears in chapters 18, 20-24, 26-28, and volume 5's extra chapter] Genos' most commonly equipped set of arms for half of the story so far, its last appearance being in volume 5. Genos never used this set of arms for battle alone, however, as he only ever used Sets 5 and 6 along with this set of arms, so Upgrade 1 may have specifically been built with the usage of sets 5 and 6 in mind. Perhaps Set 3 was too energy intensive to be used for regular battle?
- Set 5 (Suitcase Prototype) - [Appears in chapter 21] Used by Genos against the meteor, who mentioned that it was only at the prototype stage. Its inactive mode is in the form of a suitcase.
- Set 6 (Suitcase) - [Appears in chapters 25-27] First seen in chapter 25, but is not equipped until chapter 26. Is an improved version of Set 5 and has a smoother, rounder appearance to it compared to Set 5's blocky design.
- Set 7 (Rocket Arms) - [Appears in chapters 38 and 40] Used in the battle against G4. The forearms are attached to the main body by a cable and are propelled by the force of the explosive rockets built into them to strike the enemy before being retracted. When Genos' forearm was later sliced off by G4, he was able to shoot out and use the cable to entangle G4, which may mean that he can manipulate the cable's movements to some extent.
- Set 8 (Unique Extra Chapter Arms) - [Appears in chapter 39's cover and volume 8's extra chapter] Its only appearance in the main story is on chapter 39's cover. This set of arms was exclusively used against Grizzly Nyah.
- Set 9 (Upgrade 2) - [Appears in chapters 42-44] Used in the fight against Sonic. Its design similarities to Set 10 implies this set to be an intermediary point between Set 4 and Set 10.
- Set 10 (Upgrade 3) - [Appears in chapters 45-47, 51, 54-55, and volume 10's extra chapter] Still unused in combat, but possibly Genos' strongest set of arms at the present time. Has a similar design to the set of arms Genos Spoiler Comes with heat and shock proof hair.