I always have a thought to go and talk like Spongebob Squarepants or some other famous cartoon (even Disney) character all day long. But I am curious how exactly am I going to do that. Any ideas may help!!
Tom kenny is a legend, most of the roles he's done you likely wouldn't recognise him unless on the lookout specifically. What your voice sounds like for most people is fairly hard wired or programmed in infancy - it's called prosody. There are many factors you may be able to control with sufficient training, eg in the form of attempted mimicry or singing lessons, but certain properties of resonance and the vocal chords are immutable, so a perfect match is unlikely. But then there's no precise definition of uniqueness either, an iconic voice builds itself up through recognition.