This feature was so incredibly good, I'm surprised they didn't reuse it in every mainline Pokémon game afterwards. Imagine all the mandatory "trainer schools" you find in the 2nd city in every mainline game, but with actual lessons telling you IN DETAIL all the the finer things about Pokémon that the game would otherwise not clearly tell you, like what STAB moves are, damage multipliers, weather effects, the differences between Physical and Special moves, advanced strategies coupled together with certain held items, or hell, even the ancient secret combo of Defense Curl into Rollout, and then having battles in which you put the theory you just learned to practice.