You can't get Shaymin in Heartgold and/or Soulsilver without cheats.
Shaymin can't be naturally obtained, but can be transfered via a fourth generation game(d/p/pt and hg/ss)
No but, there is a Pokemon modifier code for HG/SS/PLT/D/P for HG/SS it'll give you 493 master balls and 100 ultra balls dispose the required number say, Shaymin dispose 2 master balls walk in tall grass then a wild shaymin appeared. Hope this helps.
you need a fateful encounter shaymin, and then talk to the lady in floroma town(pt) or the lady in goldenrod flower shop(hg/ss)
Use the Gracidea Flower, which is obtained in Floaroma Town in the flower shop. Or for HG/SS, you must go to the Goldenrod Flower Shop and do the same. Show a legit shaymin to the girl in the shop, and she'll give you the flower, which you must use on the shaymin in order to transform it from 5 in the morning to eight in the night. :3
You won't get it. you can only get the Gracidea flower in Pokemon Platinum. If you got the shaymin from diamond and put it in platinum it wouldn't work, you have to get a event shaymin from mystery gift or go to toys'rus at certain times. You can also get it in HG/SS in the flower shop in goldenrod city. that also involves the event shaymin.
You can obtain the gracidea flower in one condition. You have to transfer the Shaymin from the Nintendo Event or from Oak's Letter via Mystery Gift in Pokemon Platinum. So first have the Shaymin in either Platinum, HG or SS and transfer it to your White game. PS. You needed 2 DS to transfer.
There is not really a code but if you talk to a girl in D/P/PT you can get a flower that will change shaymin's form then trade it into HG/SS. Hope this helps!
Grass type. However, shaymin has an alternate form, sky forme. This makes it grass and flying type. You have to have the gracidea flower in order to change forme, but it only works between 5 in the morning to eight in the evening. The gracidea can either be found in the "Pick A Peck of Flowers" (D/P) shop or "Flower Shop" (HG, SS). :3
First you need to get the Shaymin from the 11th movie mystery gift event. Then (in Diamond/Pearl) go to the flower shop in Floaroma town. talk to one of the girls and she will give you a Gracidea flower. In HG and SS, you need that 11th movie Shaymin and go to the flower shop in Goldenrod city (northeastern house, near corner)
no
Shaymin is number 492
In DP, go to the flower shop. The shaymin MUST be an event shaymin. :3