Pokémon Ruby Tips

Increase Pokeball capure rate
When you choose the pokeball from the item pocket press Up & B-button at the same time twice, hold the keys after the second press
Up & B-button
Up & B-button (press and hold)

* note
this has to be done bewteen the black/blank screen, from the time you choose the pokeball, and the time the action screen reappears

It will increase the catch rate to about 90%, I've even caught pokemon with full health!

*also works better if the pokemon throwing the pokeball is on an higher level