Whimsicott has Prankster, which gives +1 priority to status moves. That is it niche. It can cripple Scarfed speed monsters with Stun Spore before they could move. It can trap with Encore or Taunt to keep Pokes from setting up. Offensively, it's not there. It is also fast all on it's own with base 116 Speed. It's role is supporter.
Lillagant is not bad. 110 base Sp. Attack and 90 Speed is not the worst. However, if you feel it is too low for you, it has Quiver Dance to rectify it. After 1 or 2 of those, it will rip faces off and stay in long with Giga Drain. Works great in Sun teams.