There is a special event but it has passed.
You have to raise 2 magikarps to lv. 100 in the day-care and they both have to have a leaf crown and one must be shiny.
You cannot catch Celebi on Pokemon Black. The only way to obtain one is to trade with someone else or transfer it from a Gen IV game.
They are not in Pokemon HeartGold
You cannot get Dialga in HeartGold version.
you can't get sinnoh in heartgold.
Hoenn is not in heartgold version, only johto and kanto are in heartgold, hoenn is in emerald
HeartGold is the correct title.
You have to trade it to HeartGold from P/D/Pt
you can catch lugia in whil islands in heartgold
Only by trading a Squirtle to HeartGold.
there is no Pokemon Mansion in Heartgold.
There is no TM transform in Pokemon HeartGold