I liked Togekiss. She did not feel unneeded. They could have kept Ambipom but Togekiss was better. I liked both her moveset, her personality, the episode she first appeared in and when she saved Piplup from Gibles Draco Meteor. No she was not unneeded. You could ask if Gible was unneeded too as Ash got it in the end of the series. They could have kept Gliscor on his team too. But both Gible and Togekiss got at least one important battle even if they were introduced late and both got nice movesets and a good personality.