My thought process is that the quicker I use it the better chance I have of getting to use it twice
Hitthepin vs Chessnerd1320 | Game 4 of the First KOTL All Stars Tournament!

Throw my sickle into his face.
It hits Omega Flowey in the face. It just laughs at you.
I Pellet Storm at a height where he cannot duck or jump and then drop a Flowey Bomb, then summon vines to attack you if you try to destroy the pellets.
In that case I make it so that he would have to duck, but then the vines attack him when he tries to duck/run out of the radius of the Pellet Storm

I block the pellets with my oversized hammer, run very far away from your bomb, then use my sickle to chop your vines.
I'm still coming up with a strategy.
Fine. Omega Flowey.
you can FIT to get a strategy. Omega Flowey has a really large charge time, but ok.
Flowey suddenly morphs into something... crazy. Fight.