While I’m more than confident to work alone, I however, do recommend as a minimum; and include an assistant as part of my base package. A wedding can be a very hectic/chaotic day (behind the scenes) with my main focus on covering the photography plan and capturing your day as much as possible. It makes sense for me to have a ‘hand’.
Having an assistant creates a number of advantages. They help with setting up and organising equipment, hold lighting  and modifiers, keeping track of what still needs to be photographed, keeping an eye on the surrounding activity (spotting photo opportunities), help with organising groups and liasing with other vendors. Essentially they are an extra pair of hands to carry out tasks to leave me the flexibility to be totally focused on your photography.
Second Photographer
Somthing else I also strongly recommend, is that of using an addtional experienced second photographer. This adds a lot more variety to your photographs of what’s captured througout the day. They can cover aspects (two places at the same time; different angles – e.g. Back of the ceremony, drinks reception while I’m covering couple portraits)
They’re also a backup/contingency as they will have their own equipment too and say for example there is travelling between venues, they can be sent in advance to cover arrivals. I use a regular set of photographers that I work with. All of them are photographers in their own right and I trust their abilities as much as my own.
I would normally discuss the option of a second photographer during your consultation, once I know more about your wishes.