Having TWIN boys 3 years ago, I leaned what was necessary and what wasn't. Bouncy seat, Bumbo/beebeepod seats, monitor, Bibs, diapers, formula & bottles, jumparoo, onsies, carseat/carrier, stroller and a crib/pack-n-play.
We had toys and clothes galore, and these were items we could not live without. All the other stuff sat in a corner untouched, and sold at yardsales or given away. so much money spent. Warmers, cookers, steam cleaners, all of that stayed in boxes.