to get the legendary dogs you have to choose the certain pokemon but to find them is
random just like latias and latios on emerald.

if u beat the elite 4....the legedary dogs will roame in kanto.....but its random....and u
must hav ur master ball..coz they fled if encounter them...

Now, you first must defeat the Elite 4. Now, Pokemon_Deoxys information is correct, but
there's more. For one, DO NOT, I repeat, DO NOT USE A POKEMON THAT HAS MEAN LOOK OR ANY
OTHER POKEMON THAT HAS A MOVE THAT DOESN'T LET A WILD POKEMON FLEE!!! The reason why is
that Entie and Raikou have Roar. If they use that, they're LOST FOREVER!!! Suicune is
different, he doesn't have Roar so you can use mean look on him. Also, it also depends on
your starter. If it's Bulbasour, then I think it's entie, squirtle is Raikou, and
Charmander is
Suicune!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

actually you can look at it (if u already seen it) on your pokedex and itll show its
current location. unfortuantely if u go where it is it will be somewhere different then.
so go near it but not too close and search in some gr***