With Brilliant Diamond and Shining Pearl on the horizon, regional Pokédexes are currently a hot topic, largely thanks to how... interesting the initial Sinnoh Pokédex was. Reflecting on what the previous Pokédexes did right and wrong could be an interesting course of discussion.
What makes a Pokédex good? The Kanto and Johto Pokédexes included every Pokémon that existed at the time, but that might not necessarily make them better than the latter ones. The Kalos dex is currently the biggest with 457 Pokémon, though the Galar dex is bigger if you include the Isle of Armor and Crown Tundra. Variety is obviously important, but the distribution of Pokémon and when you can get them could also be a factor; most people don't want to see Rattata and Wingull on every route, after all.
For extra points, mention something other than DP in the worst column.
What makes a Pokédex good? The Kanto and Johto Pokédexes included every Pokémon that existed at the time, but that might not necessarily make them better than the latter ones. The Kalos dex is currently the biggest with 457 Pokémon, though the Galar dex is bigger if you include the Isle of Armor and Crown Tundra. Variety is obviously important, but the distribution of Pokémon and when you can get them could also be a factor; most people don't want to see Rattata and Wingull on every route, after all.