Elemental
"HeartGold" features the fire-type Pokemon Growlithe and Arcanine, while "SoulSilver" offers Vulpix and Ninetales. "Soulsilver" only contains two exclusive water Pokemon, Kabuto and Kabutops; "HeartGold" has Mantine, Mantyke, Omanyte and Omastar. The latter two are also rock types, much like the rock/bug duo Anorith and Armaldo, which are both exclusive to "HeartGold." Lileep and Cradily, two rock/grass dual types, are exclusive to "SoulSilver." The only exclusive ice type is "Delibird," which is found in "SoulSilver."
Supernatural
The dark and ghost types are limited to Sableye in "HeartGold." Though other Pokemon of these two rare types are available, Sableye is the only one that is exclusive to either game. Baltoy and Claydol, two "HeartGold" exclusive dual-type Pokemon, are both ground and psychic. There are no other supernatural exclusives found in either game.
Miscellaneous
The only two exclusive fighting-type Pokemon are Mankey and Primeape, both in "HeartGold." The "HeartGold" bugs Spinarak and Ariados have the secondary type Poison, unlike their "SoulSilver" flying counterparts Ledyba and Ledian. "HeartGold" also features four more ground-based Pokemon: Gligar, Gliscor, Phanpy and Donphan, the first two of which are also flying types. By comparison, "SoulSilver" features no non-legendary ground types. Instead, "SoulSilver" has a number of special exclusives, including the normal types Meowth, Persian, Teddiursa and Ursaring and the steel types Skarmory and Mawile.
Legendary
Each game offers one exclusive legendary Pokemon. "HeartGold" features the incredibly powerful Kyogre, which Team Aqua attempts to summon and control in previous games. Kyogre also appears on the box for "Pokemon Sapphire" and serves as a mascot for that game. Kyogre's ancient enemy Groudon is exclusive to "SoulSilver." Like Kyogre, Groudon featured heavily in the plot of previous games as Team Magma attempted to summon it to lower sea levels. Groudon was the mascot for "Pokemon Ruby."