I don’t know if I’m the only person who’s thought of this, but the search for the Green Ninja is a lot like Mask of Light from Bionicle. It’s prophesied that there will be another Ninja who will rise-up to defeat the dark lord, and the Ninja need to discover who it is. The obvious difference is that the ninja thought one of them would be the Green Ninja and that there wasn’t direct conflict (side-missions and The Great Devourer before the Final Showdown with the Overlord (playing the part of Makuta in this case).
Although, Takanuva is far less OP than young Garmadon, here.
Recall, during Lloyd’s training, as a child no less, he broke a bunch of boards, and tore through the floor, to which Cole said “That was the power of the Scythe of Quakes!” That, as well as the intro with Lloyd in it, and other things seems to suggest that Lloyd not only had his Green Energy powers, his Golden Light powers, but also all four elemental powers!
I mean, Takanuva may have had the one type of move that was super effective on Makuta, but you didn’t see him using Fire, Water, Earth, Stone, Air, and Ice!
First, notice that green is the most powerful in Ninjago. Think about that. Second, lego does have similar beginnings for their adventure lines (Brother vs Brother), but each has a different story progression.