How to take over a gym without a battle

Here is a tips for taking over a gym without a battle.

update 23/08/2016

When players see a powerful defender in a gym

3,000 CP Dragonite in one of the Pokemon players do not want to see in a gym. It is too strong to fight against to it. Even if beating it and taking over the gym successfully, players' Pokemon get injured and need Potions and Revives. If there is a trick for taking over (or snatching) the gym without battle, that would be very helpful.

How to take gyms over without battles

In Pokemon Go, when the prestige of the gym reaches to 0, it lose its color of the team and can be taken over. Usually, players have to beat defenders in the gym to decrease the prestige. However, there is a tip for putting your Pokemon in the gym as a defender without fighting.

Find gyms attacked by other players

Gyms sparking or being struck by lightning are under attack by other players. That means the gym may be taken control and the color of it changes into white or no color.
Sometimes you can put your Pokemon in such gyms. Timing is the most important.

Tap the icon at the bottom left corner of the screen

Once you could enter the gym, tap the icon at the bottom left corner in the gym display to put your Pokemon. Now you could occupy the gym without beating defenders.

Note: Most of players do not like you to snatch gyms!

Many players consider this gym snatching techniques as unfair, however there is no official regulations currently. It is up to you whether you use the technique or not.