no they can not come back the best way for you to get thm is to save before vs them
yes you need to get the 3 legenderies regice regirock and registeel which can be found on Pokemon emerald ruby and Sapphire
There are tons of rare Pokemon, like misdreavus fo example. But if you get the national dex and go to Dawn's/ Lucas's house and talk to the little girl she'll tell you where to get a rare Pokemon every night.
Pretty much all except the legenderies
yes of course just register his fc in pal pad and you both enter to the room in the floor under the pokecenter. name:MOR fc:360997967253 my email is:edenmame@walla.com what legenderies do you have and Pokemon from johto and kanto? send me a message with the answer.
the ones you can catch are: groudon, kyogre, rayquaza, regirock, regice, registeel, latios, latias.
The best water Pokemon in Pokemon emerald I believe is Kyogre. kyogre is probably the stongest but i prefer a swampert if you don't like legenderies
There is no rental Pokemon in in Pokemon platinum
You cant get Pokemon from Pokemon ranger to platinum!
how to get a togepi in Pokemon platinum
no you cant find deoxys in sapphire. but u can go to 4shared and download a game called Pokemon sharrowns.in it you can catch most of all legenderies.
There is no grunt that you can give a Pokemon to in Pokemon platinum.
buy the Pokemon platinum book