Rouge may like Knux, but he definitely don't like her. In the Archie comics of Sonic, Knuckles already had a g/f - a pink echidna named Julie-Su. And she came around long before Sonic Adventure 1! Also, Amy is not 13 years old. She is actually 10. Besides, before Amy appeared, Sonic had a love interest on his TV series.
Super Mario Bros. are cool like sunglasses!