The Legend of Zelda: Link's Awakening for Nintendo Switch has introduced some quality of life improvements regarding the control scheme that wasn't present in the original Game Boy version of the game. The Game Boy only had four buttons, which affected the inventory management aspect of the game to an annoying degree.
The Game Boy version of Link's Awakening forced the player to manually equip almost every item in the game, including the sword and shield. The dungeons in the game often required a mixture of items to proceed (most notably the Pegasus Boots and Roc's Feather), which involved a lot of messing around with menus. The Nintendo Switch version of Link's Awakening has improved the inventory management in the game with the aid of the extra available buttons. Link will now always have his sword and shield equipped, as well as the Power Bracelet after he acquires it. The Pegasus Boots are also linked to the L button at all times after they are found.
The inventory management in the Nintendo Switch version of Link's Awakening isn't as tedious as in the original game, but there are a couple of items that the player should keep ready as often possible.
Roc's Feather
Roc's Feather allows Link to jump, which gives him an added layer of mobility and a more reliable way of avoiding attacks than relying on just his shield. It would have made sense for the developers to link Roc's Feather to a button in the same way as the Pegasus Boots, as they are often used in tandem with each other, but they didn't, so the player should keep this equipped at all times.
A Fairy Bottle
One of the new additions to Link's Awakening is the Fairy Bottle, which wasn't present in the original version of the game. The Fairy Bottles allow Link to capture healing fairies that he finds in the wild in order to save them for later.
The reason why Link needs to keep these on-hand is that they don't work automatically. If the player perishes with a Fairy Bottle equipped, then they will still die, which is why one should be kept around in case Link's health drops to critical levels.
Secret Medicine
Secret Medicine is the item that will save Link's life if he runs out of hearts, acting in a similar role to how Bottles and fairies work in later games.
Secret Medicine is a one-shot item and it's tricky to find. It's impossible to carry more than one dose at a time, which means that players might be forced to leave some behind in dungeons. It's worth noting where the unused Secret Medicines can be found, as players can go back later to claim it if they use their current dose during a boss battle.
The Shovel (After Acquiring The Seashell Sensor)
The Shovel can be purchased from the store in Mabe Village. There are numerous ground tiles on Koholint Island that can be dug up by the player, but that would take all day.
The Shovel becomes a lot more useful after the player acquires the Seashell Sensor, which is given to them in the Seashell Mansion after acquiring twenty Seashells. The Seashell Sensor will react when the player is near a hidden Seashell. Since many of them are buried, it becomes handy to keep the Shovel ready at all times when exploring Koholint Island.