Re: 赤ずきんちゃんと不思議な洞窟
Ah-ha. The spiders were a bother (and stupidly tanky), but I was used enough to using buffs and items at that point that most of their hits don't actually do too much damage. It might be just me being improperly equipped at that point, but the Nemu fight carried the very real risk of getting nuked from full to zero courtesy of the bubble spell (for Tyrol, obviously, though Tranced Tink has low enough HP that she's at risk as well).
Tentacles are probably the hardest earlygame boss by far, mostly since you only have Tyrol alone and those SP drains. I resorted to spamming the Defend command from the bracelet found in the fire area, since the damage reduction lasts two turns, and buying and using healing items from the fairy village since the mushrooms just aren't enough.
...I still have no idea what the slug and worm bosses are. I only know of the insect, the blue slime, the red slime, the tentacle, the queen matango, the drain/maneater plant, the giant armored pillbug, the spiders, the two-headed snake and Nemu.
EDIT: loaded a save just before taking down the big spider boss, and confirmed that you can only access Cynthia's dreamworld after defeating the spider. Unfortunately.