I've seen a lot of people online offering Diancie Eggs for trade, so is this true? Or are they trading Magikarp Eggs?
There hasnt been a Diancie egg event nor can you breed Diancie, so the only wat to acquire a Diancie egg is via hacking.
no its impossible to receive a diancie egg since its genderless even breeder with a ditto you will get no egg
so there probably giving away magikarp eggs like you said
hope I helped
source: I tried breeding diancie