here's ABY's tip on how to get around Destiny Bond.
First off, Destiny Bond is speed 0 priority, so speed's the main issue. That means Gengar could run Destiny Bond easily if desired.
So how do you get around this tricky move? Well, if they're faster and use it when they have little health, then there's nothing you can do if you're using an attacking move. However, status conditions like poison and burn do NOT set off Destiny Bond, so that's the first way. Sandstorm/Hail is the 2nd way. Lastly, your option is to just wait it out until they're out of Destiny Bonds. This can be hard due to trickery.
That's all I know about Destiny Bond; using weather and status gets around it.