normal:
1. Ho-oh
2. Lugia
3. raikou
4. entei
5. latias
6. lugia
7. kyogre
8. rayquaza
9. articuno
10. zapdos
11. moltres
12. mewtwo
13. suicune
14. latios
events:
1. giratina, palkia or dialga
4. mew
5. celebi
14 normal + 5 events = 19
ho-oh
In heartgold you will get Ho-Oh.You catch him in bell tower.Good luck catching him:-) and you get lugia in whirl islands from the silver wing someone gives you in pewter city and you get mewtwo after beating the elite four in cerulean cave Now enjoy and kyogre after you beat red at the top of mt silver professor oak or elm gives you the blue orb and you find him somewhere in the entrance to the sfari zone in cinnawood city
Go to the top of a tower some place
there are many legendary Pokemon in Pokemon heartgold, but the best is HO-OH
I put a link to a guide all about legendary pokemon in HeartGold in the related links.
Moltres is the only legendary Pokemon in Mt. Silver for HeartGold / SoulSilver only.
In HeartGold you can catch Kyogre.
Articuno
mew
I don't think you can refight any legendary Pokemon except the wandering dogs.
migrate and trade
Kyogre is only available for Pokemon: Sapphire on the GBA. Ho-Oh is the legendary pokemon available to you in HeartGold.
No legendary can lay an egg except for manaphy which gives an egg to phione and you can not get manaphy or phione in heartgold
yes at supercheats.com/pokemon heartgold action replay codes
Ho-ohLugiaCelebiJirachiLatiasLatiosSuicuneRaikouEnteiZapdosMoltresArticunoMewtwoKyogre-HeartgoldGroudon-SoulsilverRayquazaPalkiaDialgaGiratina