what is the best and sturdiest way to stack a wedding cake? By using Separators to divide the cakes, or just direct stacked on one another? Any links to advise me to?
You have to use a support system. Separator plates alone won't support the cake, neither will directly stacking on one another. It's what you use INSIDE the cake that keeps the above cake(s) from smashing the lower cake(s). You need to use your choice of dowels, bubble tea straws, hidden pillars, etc. Check this out: