Although Reeka and Draggle wish to impress their mother they are not truly malevolent villains, however they go along with Hydia's plan to unleash the Smooze and destroy all of Ponyvile in order to try and appease their mother: during the Smooze's attack on Ponyville Reeka and Draggle ride the monster and sing the iconic "Nothing Can Stop The Smooze" song as they gloat over their seemingly effortless victory.
In the end Reeka and Draggle recieve the same punishment as their more malevolent mother when the Smooze is defeated by the Flutter Ponies and dumped into a volcano, effectively destroying the Smooze and imprisoning the witches (though they would return in the "Fall of Flutter Valley").
Reeka and Draggle's Songs"I'll Do The Dirty Work" - this song is basically an argument between the two sisters, who try to convince the other to collect a dangerous ingredient for Hydia's spell but neither are quite clever enough to do so, resulting in this musical "tug of war".
In line with their personalities they are not shown as overly malevolent in this song but are still wicked witches and slightly spoiled brats, they are also seen collecting the parts that would be used later to create the Smooze.
"Nothing Can Stop The Smooze" - a more traditional "Villain Song" in which Reeka and Draggle gloat over the immenent destruction of Ponyvile as they ride the Smooze across Ponyvile, destroying everything in their path: this song is shared however with the Smooze itself, who delivers a few lines (mostly about how the Ponies can't defeat him).
End of Flutter Valley
sometime after the events of the movie Reeka and Draggle would return alongside their mother and? a group of giant bees to exact revenge on the ponies for their previous defeat - causing great chaos in what would be a 10-part episode of the My Little Pony TV series. In the end the witches' plans were foiled, and the Flutter Ponies blew them away with Utter Flutter, to an unknown fate.