"♪Well, your pal Flowey hasn't always been Godlike…
…I was a power-lacking flower, once…
…Now, I know you didn't expect me to strike…
…'Cause I'm unpredictable, baby~…
…Did your goatmom say 'Listen to your heart?'
'Be as loving as your are skilled?'
I need four words to tear her argument apart:
Kill or be killed.
(I'd rather be…)
Ruthless~!
Like an authoritarian dictator!
(Punch traitors, 'til their mouths are…)
Toothless~!
Your determination's strong, but mine's greater!
(I'm such hater, don't you know…)
You broke your rule not to fight,
To weaken King Asgore!
(You may have stopped a war, but…)
I took the SOULs and reached heights
Of might not seen before!
(Mmmm, SOULs galore~!)
I just need one one more…
And I'm thinkin' of yours~…♪"

battle begins

that is some really smooth animation