I would recommend using a Quick Ball on the first turn, it has a likely chance of catching a Pokemon, but it won't always guarantee it. Master Balls also can catch a Pokemon without fail, but they are meant to be used sparingly and wisely, primarily on a roaming legendary or a difficult Pokemon with a much higher level. Aside from the Master Ball, every Pokeball has a chance of failing, so there's really not much of a way to catch every Pokemon 100%.
yes but you have to catch one at a time
Unfortunately, you have to catch, trade, or somehow own every Pokemon in the pokedex. If you had it at one time and traded it, it still is in your pokedex.
catch it
Catch 'em all
YES!!!!!!!! all you have to do is see all the Pokemon and catch the ones you can catch in the game!!!
Of course you can!
No to get Cyndaquil you must catch all Pokemon from that region, because if you have to catch every single Pokemon, won't you already have Cyndaquil?
Use Action Replay
You can battle your friends, catch all the Pokemon you have seen, trade with some people perhaps. Max out all of your Pokemon if you have time.
if you don't have that Pokemon just catch it and evolve it
CATCH THEM AND TRADE FROM SAPPHIRE
You catch and evolve all of the Pokemon you catch :P