Once you’ve beaten your legendary raid boss, you’re probably very excited to catch it. Unfortunately, many inexperienced players struggle with this part and have had many raid bosses run away. Learning how to throw balls properly can increase the chances of walking away from the raid with a Legendary Pokemon rather than a disappointed frown.
For casual players, the erratic movement of raid bosses makes them miss throws and waste balls. This makes players tempted to use Nanab berries to calm the raid boss down rather than Golden Razz berries which award a 2.5 multiplier to catch rates*. The first thing such players should learn is how to make sure they always hit the Pokemon so that the more optimal Golden Razz berry can be used for every throw.
As you can see from the video above, when a Pokemon attacks, its capture ring disappears. If a ball hits the Pokemon at this time, it would bounce off and be wasted. Attacks always last 2 seconds and after an attack, the capture ring always reappears for at least 0.6 seconds.
During these 0.6 seconds, the Pokemon will also stay in the same spot and not jump or fly around. This means a player who times their ball to land in this window will not have to worry about missing the Pokemon or having their ball bounce away. However, it also takes 0.5 to 0.9 seconds for a ball to travel to the Pokemon once released meaning that a ball released during this window may end up being blocked by a second attack. Each attack always lasts 2 seconds and is signaled by a flash with white lines moving out from the Pokemon. Plan to release the ball toward the end of the attack to make sure it lands within the 0.6 second window.
These two images were taken from the video above. The image on the left is the frame immediately before Articuno started its attack and the image on the right is the frame immediately after the attack. As you can see, the size of the red circle is almost exactly the same (the one on the right is actually slightly smaller because it is one frame later in the sequence).
This is because after an attack, the circle will return to its last known size. If you stop touching the ball at any time, this will be the size of the ring when it reappears if you throw the ball to land after an attack. You must land the ball within the red ring to get a throw bonus, but the smaller the ring, the bigger the capture rate multiplier. Therefore, try to balance between setting the ring small enough to get a good bonus and large enough to actually land the ball inside.
If you are comfortable with the two skills above, learn to do it with a curveball. Curves add a 1.7 multiplier to capture rates so skilled trainers always curve. If you haven't ever thrown a curveball before, practice a bit on regular catches before trying it out on a raid boss. Putting it all together means your throws will look something like this:
The flying legendaries can attack at two different heights but always in the middle of the screen. You will need to throw farther to hit the legendary when it is high up.
Sometimes you will have to wait a bit for the Pokemon to attack. Patience is key if you don't want to risk missing the Pokemon with your Premier Ball.
Lugia is moving when the circle reappears. It starts high and then moves downward. Even though the circle is quite large, you may want to throw the ball a little higher to make sure you get it inside the ring.
Moltres’s attack involves flying in a circular shape. Make sure you aim for where it ends up and not where it is when you release the ball. Throw the ball before it returns to the center or the ball may get blocked by a second attack.