Wasn't there a movie with characters similar to the ones in suicide squad a few years ago? It seems like a sequel, especially the harley quinn character.
Wouldn't have been a movie. The upcoming Suicide Squad film will be Harley Quinn's silver screen debut. Could be possible you are thinking of the first Lego Batman film, which does have Harley Quinn and a couple other Suicide Squad characters in it.
That said, all the above are animated/direct-to-tv movies, so unless you remember that aspect, I'm doubting this is what you're thinking of.