As I have been packing away the baby stuff to make room for three mobile little girls, I have been reflecting on how we managed to minimize the amount of "gear" we needed. There are almost no items that weren't used, and used a lot. It's quite amazing how little babies really need in the first few months, even when you have three of them.
For what it's worth, my list of essential items for triplets:
A local support group. Seriously, even if you are not the support group type, the advice and understanding (not to mention the used clothes and baby items) that you will get from veteran parents of multiples is invaluable. There are also lots of triplet blogs with different approaches and experiences.
Help. My mother-in-law lived with us for the first six months. Having her here allowed us to be the parents we wanted to be: every baby got held for every feeding and rarely did anyone have to cry while waiting for a sister to be fed/changed/bathed/soothed. Believe me, there was still plenty of crying, but everyone's needs got met in a gentle and loving way.
Diapers, wipes, some kind of diaper cream. I couldn't talk my husband into using cloth diapers but know other triplet families who did.
A dozen big flannel or muslin receiving blankets for swaddling. Our girls loved being swaddled until they could actually bust out and get their arms free at about 6 months.
A fuzzy blanket each for wrapping the baby in to take places and throwing over the car seat.
Sleepers and the little diaper shirts (we didn't use onsies because they just got dirty and were a pain to get on/off when the girls were small. If you do laundry every 2-3 days, you can easily manage with a dozen of each. My girls didn't wear "real clothes" for weeks.
Triplet moms to be: don't let anyone talk you out of nursing/pumping! I nursed two babies for six months and pumped for all three until they were ten months. I had a great milk supply (~75% of what they needed) and found it very manageable. That said, I don't know any triplet mom who was able to exclusively nurse all three from day one. You may be able to get there eventually (I wasn't), but you will likely work towards it over the the period of weeks or even months. Rent a hospital grade pump, it makes a huge difference.
A few different types of bottles and nipples to see what the babies like. I thought I would use glass bottles but didn't like them at all and am so happy I bought three and not three dozen.
Co-sleeper for having the babies sleep in your room. We got one that converts to a pack and play. Our girls didn't sleep in a crib until they were ~3 months old and that was only because they grew out of the co-sleeper. The girls didn't move into separate cribs (in the same room) until they were moving around and disturbing each other, around 4 months or so.
Stroller that the infant car seats can snap into. We bought a used Triple Decker and a single and double Snap and Go and used all three for different situations. When we moved up to a stroller that the babies actually sits in I tried out a bunch to find what I liked (and bought used). By that time you know other people with babies the same age and can benefit from their product testing before you spend your own money :)
For winter babies, the Bundle Me zipped covers or something similar for the infant car seats would have been awesome. By the time I realized how helpful they would have been it was nearly spring, so I didn't buy any.
I bought two slings, a Moby wrap and a Maya wrap and someone gave us a Baby Bjorn. The Moby was easier for me to carry two babies in but it was always a little awkward. I had visions of wearing one or two babies while wrangling the third but it didn't really work for me. I found that it wasn't possible for me to bend and lift a baby while making sure the other two remained correctly positioned in the sling (i.e. necks in neutral position and able to breathe). I did use the Baby Bjorn a lot as I walked our refluxy baby for hours (and weeks) around the neighborhood in the evenings.
Boppy pillows. Love the Boppy; great for nursing, bottle feeding two babies (one on either side of you) while nursing the third. They definitely helped me keep all three babies close during feeding times and when I didn't have a free hand.
Bouncy seats - the papasan style ones are great for newborns and up and our girls lived in these for months. So, so helpful for keeping one or two babies nearby and happy while feeding the third, or safely immobilized while giving one a bath or changing a diaper. We were given some like these from another triplet family.
Cradle swing - we had one baby who had reflux and wore ours out. It was this one and I bought it used from a nearby triplet family one desperate afternoon.
A doorway jumper. We have two that we put in doorways that are at right angles to each other and use them every day. They love to jump and laugh at each other and even the non-jumping baby gets in on the fun by crawling around the feet of the two jumpers.
I didn't buy high chairs until we were ready to start solid food at 6 months and then found ones that stack so we could fit them in our tiny kitchen.
Once the girls became more aware of their surroundings we started adding books, rattles, soft toys and two play mats/gyms but even the mats have been packed away (not the books and toys, of course).
Really, that's all we "needed" for the newborn/infant months. They really did go by in a flash. Who are these little people living in my house and where did my babies go?