yes. watch the site you get the codes from
you can with action replay or go into the mystery zone with a egg but that requires action replay chip
first you cant get cheat codes into the game second if youre talking about action replay, enter the game code into the action replay
Youcan't get a second arceus unless you trade for it, get it through the GTS or use action replay(if you use action replay you can get as many as you like!!!)
You cant get a second master ball without the action replay or hacking your nintendo DS
there could be a few reasons for it. one is that the action replay does not have the game in its game roster,and another is that if you started a new game on a ds game while the action replay was in the ds, then it deletes the codes from the action replay and you have to get all of the codes all over again. i figured the second one out the hard way.
You can trade with someone who has Action Replay, or with the second games. Otherwise, you can't.
You cant without action replay
you try to download other stuff but then a second later it deletes all your files on the action replay d.s.
There is, unfortunately you will have to research the codes up yourself on sites such as cheatcodes.com or other places. Only reason is because there are so many. Then watch a Youtube video on the situation, and it should be very straightforward. I recommend not using Codes until you've beaten as much of the game as you possibly can without them.
You have to buy an action replay
Noto your first question, yes to your second.
* i dont think its possible