Not available on Sapphire. You have to trade from FireRed/LeafGreen
Entei, Suicune, and Raikou are not available in Pokemon Emerald, Ruby or Sapphire. They can be brought into the game by trading.
Suicune is not a possible starter Pokemon in emerald you must get a suicune from Pokemon firered or leafgreen.
first you pick treeko as your starter. then you beat the elite four. then you look around hoenn forhim
Suicune is a Water Type Pokemon.
The only way to obtain them is by trading from Pokemon fire red/leaf green being as you can't trade between 1st/2nd to 3rd generation.