Broly

Fat Buu most likely wouldn't know the name, but he probably did if Goku said it aloud. Shin Buu [Piccolo Prime; Gotenks Prime; Gohan Prime] would know the name of the Kamehameha Wave because he can search through Goten, Trunks, Piccolo, and Gohan's minds. He knows their past.

But to answer the question, no, the user doesn't have to say the name of the technique before it's thrown. For instance, Freeza shot his Death Beam right through Vegeta and he never took the time to say, "Death Beam!" Or what about when Cell came back from his regeneration process at King Kai's planet? The moment he came back was the very moment he shot a death beam through Trunks. I'm sure you could name all sorts of examples...

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