It isn't tricky to capture, but it takes a few encounters before you can catch it.

The legendary Pokémon that shows interest in your character.

Just repeat the same process for Raikou.

It will attack your Pokémon, but Snorlax is a tank! It won't take much damage, and it heals itself anyway with it's item, 'Leftovers'.

Once it's HP is in the red zone or a low orange, start to throw Dusk Balls and Ultra Balls at it.

There are also few other Pokémon you can use to catch Entei.

Use Snorlax's 'Block' attack to ensure that Entei cannot escape, before lowering its HP using Crunch.

Assuming that Snorlax is now your lead Pokémon, it should be Snorlax vs Entei (Snorlax lvl 50, Entei lvl 40).

Now head to where Entei is (walk or run, but do not fly!).

It's recommended to do this at night *game wise, not real-world *, as this means you can use both Ultra Balls and Dusk Balls.

Go to your GoldenRod City and buy 20 Ultra Balls and 20 Dusk Balls.

Some attempt to go after two at a time but it doesn't work nearly as well as simply choosing one and sticking to it.

Open up the PokeGear and click on the map icon, you should see the images of both legendary Pokémon on your map.

Once you have Snorlax, fly back to Johto.

Wake up the sleeping Snorlax outside of Diglett's Cave and catch it using Poke Balls that would suit the Snorlax for example, Heavy Balls (only do this after you've completed the Kanto region as well as Johto).

Here's a way that has successfully worked. Through work, however, you can beat them. You see, both Entei and Raikou will just escape from a battle whenever you try to catch them.

Well, first things first, complete the entire game before trying to capture the legendary Pokémon.

Pokemon heart gold legendary dogs