How do you catch the 3 legendary dogs in pokemon silver?

Answer 1

Their names are Entei and Raikou, and Suicine is caught later

There is also Latios in the Kanto region

You have to get them down to 1 HP (false swipe is a good TM, as it always leaves the pokemon with 1 HP )

Then throw pokeballs at it.

Ultra and Heavy work well. Dusk works at night, the Masterball will work, but there is other legendarys which are harder to get.