They don't sound anything alike, Rikku and Riku. Voicewise, I mean. Who are Evan and Rin? [At least Vanitas knows who Rin is, just not.. by that name. "that douchebag with a pink scarf" from nearly two years ago.]
I guess Braidku is suitable, but foofyku is hilarious.
Voice
I guess Braidku is suitable, but foofyku is hilarious.