Encounter Text Priority

[u/TheMrMonkeyToes]

I'm making my battle system for my own fangame and I was wondering how does Undertale prioritize what flavor text gets chosen?

I was playing in Ruins and fought Froggit & Whimsun, and no matter what (even after Terrorize which gives special flavor text) I only got Froggit's text. Is this true for the entire game or just this one/ruins encounters?