Phillipe Cantin writes:

So you want to two HC-05 modules to automatically connect together, as soon as they’re powered up and with zero code? Well this is your lucky day since this can be done using the AT+BIND command.
Let’s do this thing!
For this, you will need:
1 Arduino (I’m using UNO)
2 HC-05 modules
1 breadboard
Wires
Arduino IDE (I’m using version 1.0.5-r2)