Pokémon SoulSilver Version Tips

Status Effects
Catching hard-to-get Pokemon can be burdensome without some status effects. Every status effect has a different multiplier for the catch rate:

Sleep: 2
Freeze: 2
Paralyze: 1.5
Poison: 1.5
Burn: 1.5

As you can see, Sleep and Freeze are the most effective status ailments for catching Pokemon.