Pandaxclone2 said:
Young Link in OOT and MM would be the strongest. When you really think about it, Adult Link is still Young Link mentally, so all of Adult Link's accomplishments are Young Link's. As for Adult Link himself, he literally disappears after the events of OOT from the Adult Timeline which is why Wind Waker is in such a state and why they have no natural hero. They even use clothes as a initiation right in honor of the Hero of Time.
When Young Link comes back to his timeline, he knows a lot more about adult-hood than when he started including how to ride horses, use a bow, carry larger wallets, ect. This becomes useful to him as now he has something that not many opponents will realise; experience. To them, he may as well be a small fry who can't do much, but he is capable of much more than they think.
Majora's Mask just adds to that knowledge he already has, as he can then utilise the masks that make his roughly adult size to do things that his young body can't. Finally, in Termina the people consider a person to be mature when they reach a certain state of mind instead of body. Young Link already proves that he knows a lot more than he normally should, and even gets a Cow Hat for it when helping Cremia.
In all honesty, Young Link is as powerful as he is not because of being a powerhouse, but rather that he can use his mind to strategise and beat an opponent. This goes for all Links really, but why do you think Ganon(dorf) always loses in spite of the fact that he has the Triforce of Powe