Shroomer Noct,
Lullu and
Prunelia provide benefits that affect the wider base rather than only improving their own work. Their Partner Skills also stack with one another because each Pal provides a different effect.
Shroomer Noct
While assigned to a base,
Shroomer Noct slows the rate at which other workers lose SAN. This helps Pals remain productive for longer and reduces the amount of time they spend resting or recovering.
The effect becomes stronger through Condensing, but even an uncondensed
Shroomer Noct can improve the stability of a busy base.
It is also a versatile worker with access to Planting, Gathering, Handiwork and Lumbering. This allows it to continue contributing whenever its SAN support is not the only reason you need it.

Lullu
Lullu increases the growth speed of crops produced at the base. When fully Condensed, this becomes a huge improvement to how quickly your plantations complete each growing cycle.
It covers many of the same farming tasks as
Shroomer Noct, including Planting, Gathering and Handiwork.
Lullu can also help with Medicine Production, making it a useful general worker between crop cycles.
Faster growth becomes increasingly valuable when your base needs a steady supply of ingredients for food, medicine and breeding cakes.

Prunelia
While
Lullu makes crops grow faster,
Prunelia increases the amount collected when those crops are harvested. Using them together improves both the speed and total output of your plantations.
Prunelia can perform Handiwork, Planting, Gathering, Medicine Production and Transporting. This gives it several ways to contribute without wandering away from the farming area for unrelated jobs.
Combining
Prunelia with
Lullu creates the foundation of a highly productive farming base, while
Shroomer Noct helps the workers maintain their SAN.
