Oh, don't come at a lifelong critter-catcher with a Biology degree trying to get uppity with the frog knowledge. I'll show you things you've never seen before. "Hairy" frogs, frogs with bone claws, burrowing frogs, and frogs in every color of the rainbow, son. I've seen a bullfrog snatch a swallow straight out of the air during a field study. I know my frogs, and I like my Greninja classic, cartoony green.
All joking aside, dart frogs are pretty sweet. Greninja really isn't that crazy-looking by frog standards besides his tongue scarf. The colors of a dart frog, lanky limbs and proportions of a tree frog, and head projections of some horned frogs are all cues taken pretty directly from the natural world.