Get a pokemon with mean look(crobat,golbat) or arena trap (trapinch) to stop ''it'' from fleeing, then attempt to attack suicune until the health is lower and try devour yourself into catching it.
Yeah, you have to spot and make it hop around 4 times before you'll find it later by Bill's house AFTER you collect badges, do a barrel roll, and divide by zero As for catching the Raikou and Entei; Mean Look, then Hypnosis, followed by another good attack and False Swipe, if you have it
it is a bit off these only like that in the newer versions in the old games is a matter of luck unless you are talking about crystal version in which the creature will challenge you to a battle