You can if you want to.
you can use cheats or have a regigigas from the 11th movie
Just just hit the menu button, then it should say cheat and press that. After that, input the cheat by having a cheat, which you can look up , and after that you should be able to use the cheat if its the right one.
their are no regies in pearl or diamond besides regigigs but u need the three regies to get him in the snowpoint temple.
you may not be able to use your catalogue if you use that cheat! :(
no
Yes you can.
No u cannot use cheat codes for ''Mercenaries 2 world in flames'' due to it needing internet connection to be able to activate the cheat code(s).
you must trade them
regigigas
there the home of the regies
IN D/P and platinum after you get the regies you need to have the three regis in your party and off you go to snowpoint temple to catch regigigas
Unfortunately, you must migrate the regies from ruby or sapphire. You cannot catch them in pearl/diamond.