In HeartGold, You catch Ho-Oh earlier and at a lower level than Lugia, same thing for SS, but swapped. Other pokemon you can get are Mankey
Primeape, Growlithe, Arcanine, Spinarak, Ariados, Gligar, Mantine, Phanphy, Donphan, Sableye, Baltoy, Claydol, Kyogre, Mantke, and Gliscor.
In Soul Silver, you can catch Vulpix,Ninetales, Meowth, Persian, Ledyba, Ledian, Teddiursa, Ursarang, Delibird, Skarmory, Mawile, Gulpin, Swalot, and Groudon.
Black has Reshiram, Weedle, Kakuna, Beedril, Murkrow, Houndor, Houndoom, Shroomish, Breloom, Plusle, Huntail, Honchkrow, Gothita, Gothorita, Gothitelle, Vullaby, Mandibuzz, and Tornadus. Black also has Black City, which has trainers to battle, which you can get a lot of money from the Boss of Black City for battling them. You can also buy items (for higher prices then the Poke Mart, mind you.) But you can also buy Heart Scales there if you have enough and certain people in Black City. The Gym leader in Opelucid City is different, they're teams are almost exectly the same, execpt Drayden's pokemon are all male, while Iris' pokemon are all Female.