The most important ones dont come from pills. Those just somewhat help support the ones that do matter and can help sway the immune system a little bit. Theres so many thousands of strains and the list of things they individually do is incredibly long, perplexing, and really not even understood that well at this point. Off the shelf probiotics help some, but they are nowhere near a replacement for the real thing. The most important anaerobes cant be supplemented, they cant live in the presence of oxygen. I personally would take one transplant over a years worth of probiotics. Once the seed is planted, all you have to do is feed it, water it, and keep the garden weeded. But it has to be there in the first place.