I disagree heavily with you. Those legendaries are one of the best looking legendaries we have ever seen! Koraidon represents past and Miraidon represents future. They are both dragons and probably bikes you can ride on.
But every effect says "during this turn" it doesn't necessarily mean during the same turn you use the supporter. Or maybe I'm wrong. We have to wait for official ruling for that.
I'm not sure, but I think you can take it from your discard pile at any point of your game, (if you discard 2 cards of course) not only on the same turn you play it.