Most likely Genesect.
It's not the "last" Legendary Pokemon that you can find in Pokemon HeartGold, but most people usually catch that one last given that you need to have both Kyogre and Groudon in your party for Professor Oak to give you the Jade Orb to get to Rayquaza.
Yes in Pokemon White after you defeat the last member of the elite four you are forced to battle Zekrom. You battle Reshiram if you have Pokemon Black.
You should be able to find your Pokemon white game where you last put it.
Pokemon Black: Last gym leader is male You catch the white legedary Different wild Pokemon Pokemon White: Last gym leader is a female You catch a black legendary Different wild pokemon May be more, but these are just the most obvious ones. Only very minor things, though!
the last legendary in story mode is ryquaza and in free mode it is Latias
I think u find it near the last gym
Yes it's even the last pokemon in the Unova pokedex.
He just comes to capture him.
Try to remember where the game was the last time you played it.
all kinds of Pokemon
The fastest way is to collect every pokeon in dimond /pearl or platinum then transport every last one to black and white then collect every black and white native pokemon
In Pokemon Leafgreen or Firered, you should try and catch the one last legendary Pokemon with your master ball if you saved it. (It depends on your starter Pokemon on what legendary you can get.)