questions about the heroes of the one punch man series

hey i have some questions about the heroes of the one punch man series to be more specific metal bat i heard he starts of like a normal guy but as he fights he gets stronger and stronger to the point he can take put someone like saitama is that true and when the battle is over does he return to his normal strength level and i also like to ask how come ssitama is not a s class hero

He starts as a reallly strong guy not just a normal dude and he can get reallly strong but beating saitama is a no

His strength and power increases as he takes damage and fights. This special/supernatural ability is called fighting spirit. However, Metal Bat is still prone to knockouts and taking to much damage too fast etc. But in theory, fighting spirit would increase his power more and more and if the perfect requirements and setting took place, there is no technical limit. However, his feats even when quite injured and further down the "fighting spirit" process are quite limited compared to other top tiers in the verse.

The statement about taking on Saitama is based on ONE or Murata saying fighting spirit could temporarily move or remove(depending on translation) Metal Bats limiter.

Metal Bat is really strong, but he has a supernatural ability that makes him even stronger as the fight proceeds, called as the "Fighting Spirit", the more he gets damaged there more pumped up he becomes, those not only increasing his strength, but improving speed and his senses.

Saitama currently ranks class A.