It may appear similar to a frog, but I don't think the classic "deep and/or croaky voice" will cut it with this character. Instead, it would be better if it's dialogue is read in a smooth voice, kinda like how the text sounds in the game. The only time you really need to worry about the croaking is when they say "Ribbit Ribbit", and that only needs a little bit of croakiness. Make sure to have some fun with this one, because it's tone and usage can be varied!