Pokémon SoulSilver Version Tips

Catching Roaming Pokemon
The best way to deal with roaming pokemon (that is, ones that move around the region and run at the first opportunity) is to have a strong pokemon with moves like the following:

False Swipe
A sleep or paralysis inducing move
A trapping move (eg Mean Look)

Option 1:

Breed a female ralts with a compatible partner that knows Mean Look (eg Gastly or Duskull). Take a male offspring, keep Mean Look on it and raise it to Lv43 to learn Hypnosis. Evolve it to Gallade now and teach it False Swipe via TM.

Option 2:

Breed a female Absol with a male Umbreon that knows Mean Look. Teach the baby Absol False Swipe (TM 54, Dark Cave or Goldenrod Department Store) and Thunder Wave (TM 73, 32 points at the Battle Frontier). Now just level up the Absol.

In either case make sure to use Mean Look first so the opposing pokemon doesn't run away on the first turn (yes, they'll run even if put to sleep).