How do I reach the Crystal cave? And does anyone know how to level up Lime slime? Nevermind I found it. The crystal cave is down by the beach just go down the grass path and it is near the end of that path.
Last time I played, the Lime Slime couldn't gain levels.
Explaining is hard but the main thing is that the Slime can only grow by consuming potions. Even after a fight, the Slime will retain some points in the stats affected by the potions. Moreover, it stacks so you can feed it a lot of potions before jumping into a fight.