Giratina - Before completing your first trip through the Distortion World, you will encounter Giratina in its Origin Forme. It will be at Level 47. Giratina will revert to its Altered Forme when you leave the Distortion World, however if you enter Turnback Cave, and enter the Distortion World, you will find a Griseous Orb. Make Giratina hold it, and it will stay in its Origin Forme even when it is not in the Distortion World
Palkia & Dialga - After getting the National Dex, talk to Cynthia's grandmother in Celestic town, and then find the Lustorous and Adamant orbs in Mt. Coronet. After finding them, go to the Spear Pillar, there will be a blue or pink portal there, if you get the blue you will battle Dialga, and pink is for Palkia. After catching one, you can return to Spear Pillar again to catch the other. They will both be at Level 70.
Azelf & Uxie - Go to their respective lakes (Uxie = Lake Acuity / Azelf = Lake Valor) and surf to the cavern in the middle of the lake. When there, select it and you will battle it. They are both at Level 50.
Mesprit - As you did with both Azelf and Uxie, go to Lake Verity and enter the cavern. However, when you select Mesprit, it will flee. Mesprit is now marked as "SEEN" in your Pokedex. If you want to catch it, you must search Sinnoh, you must use the Marking Map App. on your Poketch to locate it. Do NOT fly to the location where Mesprit is at, or else the location will reset. It will be at Level 50.
Zapdos, Articuno & Moltres - After getting the National Dex, go to Prof. Oak's house in Eterna City. He will tell you that the three legendary birds are roaming Sinnoh. Once again, they will be roaming Sinnoh, so use the Marking Map on your Poketch to locate them. All three of them will be at Level 60 upon encounter.
Heatran - After getting the National Dex and completing the Stark Mountain quest, return to the heart of Stark Mountain and you will encounter Heatran at Level 50. Cresselia - After getting the National Dex, go to the ship in Canalave City, and you will gain access to Full Moon Island. Go through it to the deepest part and Cresselia will be there. Once again it will run and you will need to use the Marking Map to locate it. It is Level 50.
The Regis - Migrate the three Regis from a Gen III game (Ruby, Emerald, Sapphire etc.) and go to Snowpoint Temple. You will be allowed to enter and Regigigas will be there, asleep. Select it, and it will wake up. It is at Level 1 only, so bring your weakest Pokemon to fight it.
The other way requires an event. For that click the link below:
http://www.serebii.net/platinum/regigigas.shtml
If this link does not work, copy and paste it into your browser.
you need both ruby and Sapphire to get there. :)
The only way is to trade with someone who has one of the other starters and can trade with firered. I know that leafgreen can and so can another firered
there is no other way sorry. :(
if you want to do it without cheating you'll need a ticket to get to navel rock from a Nintendo event otherwise you can't get lugia without hacking or cheating unfortunately.
no you cannot. unless you go to the special events Nintendo does.
You cant without cheating
i dont think that you can without cheating
be a total doosh
you can't. not without cheating or a Nintendo event to get a special ticket to gain access to the island on which it resides, only legit way i know of is to trade it from Pokemon Colesseum for the Gamecube. yes you can, if you have a mystic pass which can be abtanded in a Nintendo event
you need both ruby and Sapphire to get there. :)
Unfortunately, Mew is not a catchable Pokemon in FireRed. It is impossible to catch it without a Cheating Device. Sorry, The interwebs fooled me, too.
you have to save the president of silph co. to get the master ball.
There is no possible way without hacking or cheating. I heard they are bringing Mew back in Pokemon Heart Gold and Soul Silver.
The only way is to trade with someone who has one of the other starters and can trade with firered. I know that leafgreen can and so can another firered
there is no other way sorry. :(
I'm sorry but it is impossible without a cheating device or an impromptu Nintendo Event
You can't anymore, since there's no more Nintendo Events going on.