What is little dragon in Japanese?

小さなの (chiisa na no) would be the equivalent of "little one". It is important to note, that in this context の (no) is being established as a generic noun replacement. Therefore, it's actual meaning must have been previously established in the conversation. For example, if you were asked どちらいいと思いますか？ (dochira ii to omoimasu ka, which do you think is good), you can respond with 小さなのと思います (chiisa na no to omoimasu, the small/little one).