Hey Guys! I'm back, and today I'm gonna do a little how-to Lesson. 
That's right... I'm gonna teach you to catch legendary Pokemon! Just a disclaimer, I have only caught one legendary Pokemon before. I am not going to tell you how to catch every Legendary Pokemon, but I'm going to give you tips on how to obtain them based off of my expierences. If that's all you need, lets go.
Sadly, all of the Kanto and Jhoto legendary Pokemon are uncatchable now. The only way to get them is if one day, Pokemon go gets a trading system. So, this will only work with the legendary pokemon up to whatever region they are in now. First things first, Legendary Pokemon only appear in raid battles. For those of you who are new to the game, raid Battles are when many trainers group around a gym to try to take down a more than usual powerful Pokemon. Keep in mind that you have to be at a certain power level to do this. You will know if a raid is at a gym when it shows up right next to the nearby Pokemon list, as you can see above.
The second part to catching a legendary is to get into and defeat it. Now, I was had trouble with this at first. I would battle the legendary no matter what, and I ended up wasting a lot of revives and raid passes. SO TAKE MY ADVICE- NEVER ENTER A LEGENDARY RAID BATTLE UNTIL THERE ARE AT LEAST FOURTEEN PEOPLE WAITING!!! You will not stand a chance otherwise, trust me.
Finally, here comes the hard part. Assuming that you managed to defeat the Pokemon, catching it is a whole other ballgame. You will get some rewards for defeating the raid boss in battle, but then you have a chance to catch it. Here are some tips.
*DO NOT AIM FOR INSIDE OF CIRCLE. Raid Pokemon are not like normal Pokemon. To have a better chance at getting them, try to aim outside the circle. It will help you by increasing the capture rate by about twofold.
*Gradually work your way up berry wise. Try not to use golden razz berries from the start. Only use them if the Pokemon is being particularly difficult.
*Keep a steady Hand. Nothing makes me more upset when I throw a poke ball and miss the Pokemon because I got excited. Keep a cool head, and remember, It's not the end of the world if you didn't catch it- Just look for another raid the next day.
*If you do catch it, thank your teammates. You absolutely could not have caught the Pokemon without their help. Say thanks, or if you are reading this when there is a trade system, just trade your Pokemon and trade back.
Well, that's about it. I do hope that the beloved Pokemon from the early two thousands and nineties come back sometime. Thank you for reading through to the end, and make sure to up vote, promote or follow. Keep in mind that if you do, I will help you back, weather the next day or month. Remember that Pokemon go is still cool, so get out of the closets and catch those buggers you've always wanted! Good Luck!