Standalone Mega ???!!!

Hello Everyone
If I design a proper pcb for the at-mega 2560 microcontroller is there a way that I can use it standalone in project like atmega 328 ??
What components should I use with it (like crystal oscillators or capacitors )?

Yes you can use it similar to an ATmega328. There's no real difference other than more pins and a different package. The Mega 2560 board has no magic to it. Just like the ATmega328P Arduino boards, it's only a microcontroller on a circuit board with a few necessary components and the USB hardware.

You can find a minimal ATmega2560 board schematic here: