Hello to everyone,I'm in this world so I need your help. I would ask to you for I2C I must need 2 Arduino Uno or I can also use for example, an Arduino mega and an Arduino Uno? Thank you in advance.

With I2C you should be able to use any board with any other providing both have I2C.

Assuming they use the same supply voltage.

If they use different supply voltages, level shifters can allow them to work with I2C.