That one. XD You need all three of the legendary trio, which I have two sets, but can still only summon once every few weeks. Two weeks, I think. And then you have a very small chance of summoning a Guardian of Nature egg. ^^;
Well, a trade on DC means you have to abandon the egg, and the other person will have to be faster than everyone to pick it up. That's the only way you 'trade'. But it's really risky and you lose eggs a lot that way, with other people somehow grabbing the egg before you. ^^;
I remember they were going to make a 'Transport' action on the orange dragons. I guess maybe you can transport once every week to someone with each orange dragon you have. It would be really nice, but they haven't done it yet. I wish they do.