You can transfer from Generation III to Generation IV, but you can’t transfer from Generation I or II to Generation III. This means that a Gligar from Gold, Silver, or Crystal cannot be evolved into Gliscor, because it cannot be transferred to a version that supports it. To transfer from Generation III to Generation IV, you’ll need to have received the National Pokedex in your Generation III game. Insert the GBA cartridge in your DS and select “Migrate” from the main menu of your Generation IV game. Select Gligar and five other Pokémon you want to migrate. In your Generation IV game, visit the Pal Park on Route 221 to catch your migrated Gligar.
The Razor Fang can cause your opponent to Flinch during battle, which makes it a fairly useful item regardless.
You can level up by fighting a wild Pokémon or a trainer, or by using a Rare Candy.
In HeartGold and SoulSilver, you can only get a Razor Fang from the Battle Frontier.
You can find a Razor Claw on Route 13 on the cliff to the south of Artist Zach. Route 13 becomes available after completing the story. You can find a Razor Claw at the Abundant Shrine, southwest of the trainer named Maki. You can earn a Razor Fang at the Battle Subway by winning 48 BP.
Bring a Pokémon that knows Surf and Waterfall, and travel to Route 11. You’ll find the Razor Fang to the right of Thalia. Earn 8 BP at the Pokémon World Tournament to get a Razor Fang. The Pokémon World Tournament is in Driftveil. This may be the easiest way to get a Razor Fang in the game. You can also get a Razor Fang for 8 BP at the Battle Subway as well, which becomes available later than the Pokémon World Tournament.
A Razor Fang costs 48 BP from the Battle Maison, available after beating the game. You can win a Razor Claw by playing the Balloon Popping game at the PokeMileage Club. The game costs 100 Miles, which are earned by walking in the game and trading with other players. You’ll need to play the Level 3 version of the game to get a chance at the Razor Claw.
The Battle Maison at the Battle Resort stocks Razor Fangs for 48 BP. Nearly every Mirage Island will have a Razor Fang on it, making this the easiest way to get one. Like X and Y, you can win one at the PokeMileage Club for playing the Level 3 Balloon Popping game.