The opposing Gengar used Dark Pulse! A critical hit! Dragonite lost 42.6% of its health! Dragonite used Dragon Dance! Dragonite's Attack rose! Dragonite's Speed rose!
Dark Pulse inflicts damage and has a 20% chance of causing the target to flinch.
Where is the flinch? 100% has failed? Glitch? Here is the battle video. Turn 19.
This wasn't a glitch. Dragonite was using the ability Inner Focus, which prevents flinches. I'd imagine Inner Focus is much more viable in Haxmons which is ridden with flinch moves, so maybe it's something you should expect.