Answer:
sorry pal..i dnt think there is a way....unless you have a cheat card like action replay......but you need to buy that. and platinum lets you catch moltres,articuno and zapdos aswell as dialga, palkia and garintina. but both of those reasons you have to pay..............(games are rubbish tht way arnt they????) sorry pal i would give you an answer if i could but i don't have one. if there is a way that i don't know of that you find could you reanswer this Q.???
UPDATE!!!!!
You can catch the following in these games:
DIAMOND: Dialga, Garintina, Darkrai, Arceus, Manaphy. (i think there is 1 more)
PEARL: Palkia, Garintina, Darkrai, Arceus, Manaphy. (i think there is 1 more)
PLATINUM: Palkia, Garintina, Darkrai, Arceus, Manaphy, Dialga,Moltres, Articuno, Zapdos
HEARTGOLD: Lugia, Ho-Oh, Suicune, Articuno, Zapdos, Moltres, Mewtwo, Dialga, Palkia, Garintina,Latias,Latios, Entei, Raikou.
SOULSILVER: Lugia, Ho-Oh, Suicune, Articuno, Zapdos, Moltres, Mewtwo, Dialga, Palkia, Garintina,Latias,Latios, Entei, Raikou.
HeartGold and SoulSilver have slight differences to the legendary Pokemon you can catch in the game. Here are some of these.
LUGIA:
OT: yours
ID NO: yours
HELD ITEM: none
MOVES: (when first met) Aeroblast, Raindance, Hydro pump and extrasensory.
LEVEL: (when first met) 45
HO-OH:
OT: yours
ID NO: yours
HELD ITEM: sacred ash
MOVES: (when first met) Extrasensory, sunny day, fire blast and sacred fire
LEVEL: (when first met) 45
SUICUNE:
OT: Yours
ID NO: yours
HELD ITEM: none
MOVES: (when first met) rain dance, gust, aurora beam and mist.
LEVEL: (when first met) 40
ENTEI:
OT: yours
ID NO: yours
HELD ITEM: none
MOVES: (when first met) roar, fire spin, stomp and flamethrower.
LEVEL: (when first met) 40
RAIKOU:
OT: yours
ID NO: yours
HELD ITEM: none
MOVES: (when first met) roar, quick attack, spark and reflect.
LEVEL: (when first met) 40
ARTICUNO:
OT: yours
ID NO: yours
HELD ITEM: none
MOVES: (when first met) ancient power, agility, ice beam and reflect.
LEVEL: (when first met) 50
ZAPDOS:
OT: yours
ID NO: yours
HELD ITEM: none
MOVES: (when first met) ancient power, agility, charge and discharge.
LEVEL: (when first met) 50
MOLTRES:
OT: yours
ID NO: yours
HELD ITEM: none
MOVES: (when first met) ancient power, flamethrower, safeguard and air slash.
LEVEL: (when first met) 50
MEWTWO:
OT: yours
ID NO: yours
HELD ITEM: none
MOVES: (when first met) psycho cut, amnesia, power swap and guard swap.
LEVEL: (when first met) 70
GROUDON:
OT: yours
ID NO: yours
HELD ITEM: none
MOVES: (when first met) rest. earthquake, ancient power and eruption.
LEVEL: (when first met) 50
RAYQUAZA:
OT: yours
ID NO: yours
HELD ITEM: none
MOVES: (when first met) rest, air slash, ancient power and outrage.
LEVEL: (when first met) 50
DIALGA:
OT: yours
ID NO: yours
HELD ITEM: adamant orb
MOVES: (when first met) dragon breath and scary face.
LEVEL: (when first met) 1
PALKIA:
OT: yours
ID NO: yours
HELD ITEM: lustrous orb
MOVES: (when first met) dragon breath and scary face.
LEVEL: (when first met) 1
GIRATINA:
OT: yours
ID NO: yours
HELD ITEM: griseous orb
MOVES: (when first met) dragon breath and scary face.
LEVEL: (when first met) 1
LATIOS:
OT: yours
ID NO: yours
HELD ITEM: none
MOVES: (when first met) dragonbreath, refresh, watersport and mist ball.
LEVEL: (when first met) 35
LATIAS:
OT: yours
ID NO: yours
HELD ITEM: none
MOVES: (when first met) dragonbreath, refresh, protect, luster purge.
LEVEL: (when first met) 35
HeartGold. (NOTE. there is only information on these 3 Pokemon because all the others are the same. Kyogre is there instead because Groudon is only available in soulsilver!)
LUGIA:
OT: yours
ID NO: yours
HELD ITEM: none
MOVES: (when first met) aeroblast, punishment, ancient power and safeguard.
LEVEL: (when first met) 70
HO-OH:
OT: yours
ID NO: yours
HELD ITEM: sacred ash
MOVES: (when first met) sacred fire, punishment, ancient power and safeguard.
LEVEL: (when first met) 70
KYOGRE:
OT: yours
ID NO: yours
HELD ITEM: none
MOVES: (when first met) aqua ring, ice beam, ancient power and water spout.
LEVEL: (when first met) 50
all wrote and made by me (jamie lee crawford) if there are new answers i don't mind because that's what its for! to give answers to people in need. thx, jlee.