In Dragon Quest Monsters: Joker, there's a monster that's only obtainable if you catch all the monsters in the game and fill up your Monster List. Unfortunately, the game includes this special monster in the criteria, meaning it's literally impossible to get this monster - and, in turn, 100% - without hacking.
...although you're going to have to hack the game anyways to get 100% because some of the monsters are also tied to the online multiplayer and well. You're SOL there too since the DS online servers are down.
As for the actual game, it's pretty lackluster as far as a Dragon Quest Monsters game goes because the monster list is essentially Square-Enix looking at Dragon Quest VIII and going "well this game is popular, so most of the monsters you befriend are monsters from this game!" and it honestly feels like major cost-cutting in a game that's already cutting corners by having a good chunk of the monster list being recolors of other monster models. Not the worst monster collecting game but there are far better out there.
...although you're going to have to hack the game anyways to get 100% because some of the monsters are also tied to the online multiplayer and well. You're SOL there too since the DS online servers are down.
As for the actual game, it's pretty lackluster as far as a Dragon Quest Monsters game goes because the monster list is essentially Square-Enix looking at Dragon Quest VIII and going "well this game is popular, so most of the monsters you befriend are monsters from this game!" and it honestly feels like major cost-cutting in a game that's already cutting corners by having a good chunk of the monster list being recolors of other monster models. Not the worst monster collecting game but there are far better out there.