Where to catch dugtrio in Pokemon FireRed?

If your looking for a dugtrio in FireRed it is actually quiet simple. First you go to vermillion city and keep going right, until you find a cave. while you are in that cave you will encounter a lot of diglets. But if your lucky you will find a dugtrio. If I found dugtrio and so can you. If you want to catch it you must first bring it down to low health befor catching it. or you get a repel from the mart use that in the cave and then a dugtio will show up