I want to use 6 uarts and 2 spi ans 2 IIC along with USB and ethernet. But in the pin multiplexing I cant find all these options together even if I take a MCU with all these features. Am I getting wrong somewhere or is it not possible to use all these together.
Yes, your concern is correct. Even for the Kinetis parts who has all the interface you mentioned, but they can not been enabled simultaneous. For example, the UARTs are multiplexed with SPIs. So you can only use one function at a time.