If you want to pull a specific card, having dual sets literally makes you twice as likely to pull it assuming you're willing to take advantage of that.
If not, buying an equal amount of each expansion will give you more or less the same experience as if it were one big expansion. Three of the...
I find it kind of interesting that so many users are focused on the "theme" of expansions now (both for and against, not trying to single anyone out). It used to be an uncommon praise/criticism but ever since Paradise Dragona was revealed it's suddenly become this hotly debated topic under half...
It isn't unfortunately, Everyone Explode Now also does damage to each of your Pokemon and is called "Everyone Explode" in Japanese. This is a new attack