While I do highly recommend using the below kitchenware, it is possible to be a bit flexable when making smash burgers but do be prepared for a few issues with sticking if you do.
I have found through a great deal of experience that a cast iron skillet is the best way to fry a smash burgers. This kind of pan retains heat really well and distributes it evenly, which is perfect for cooking a couple of burgers. It is also essiential that this kind of pan allows you to scrape off the burgers when cooking without too much sticking and without ruining pan itself or even worse; your'e burger now has non-stick coating cooked into it. For me this is probably the one peice of kitchenware that is a must have for this recipe. It is possible to use another high quality pan but it will most likely be more expensive and I have yet to find one that works as well. Luckily for those who don't have one, they are not too expensive and can be found on Amazon or Walmart for decent prices. Just make sure you get a size that works for the amount of burgers you want to make.
While this is not as important as the cast iron skillet, a flat metal spatula will make making your smash burgers a whole lot easier. No matter how good your pan is, the burgers will stick. In fact you want them to since this is what gives them their crispy crust. Having the flat metal spatula will allow you to really get under those burgers and get them flipped without losing any of that crust. While you can use a different kind of spatula, the flat metal is the way to go. However, if you do use something else, try to get one the is sturdy and if it has a bit of an edge to it, that will help as well.
The smash burger press is the first truly optional item on this list but it still can help simplify the process. The press is used to flatten the burger patty as thin as possible right as its put on the pan. However, this process can be done with the spatula, or as my mom used to do, a small egg pan. If you are someone on a budget, this is a great item to buy later down the line if you find yourself with a bit of extra cash. If you just aren't sure how much you will make smash burgers, then this is a great item to hold off on until you know you know they are a staple make in your house.
This last item is purely personal preference. While I will suggest putting sliced pickles, onions, lettuce, and tomatoes on your smash burgers, you can choose what you best like for your burger and you might find you have no use for these items. I am sure everyone has a knife capable of these tasks but the sharper the better since it will help you get those nice thin slices. The cutting board can easily be replaced with a plate or any kind of clean flat surface, so don't worry too much if you don't have one.