pinball ruby/sapphire

After you play a while you'll go to the ruins, there you will see an arrival sign. Jirachi will appear and you'll have 30 seconds to hit him 3 times

Chimecho can be hatched from an egg

Latias can be caught on every field on sapphire, there is a very low chance that you'll see her

oldies:

pinball

first beat all bonus levels twice with a very high score. When your map will change it will change into indigo plateau. There you'll see Mew