The mattress sold with the particular Pack ‘n Play is the best and the safest option. Still, it is more of a mattress pad that is a bit thin and hard, leading many wonders about how to make their Pack ‘n Play more comfortable for their baby.
You have a crib and lots of cute fitted sheets. Does their size also fit your Pack ‘n Play mattress? In rare cases, this is possible. But more likely, the interior dimensions of your crib and Pack ‘n Play are not the same, meaning you will need sheets of different sizes.