>>45424048>prosEmerald is the definitive game in gen III. GameFreak made it with the hope that people would be playing it year after year due to the Battle Frontier. It really is something else. You could easily max out the clock if you really liked it and tried to go and beat records again and again. This game also allows you to catch both box legends and has a few expansions in the post game, namely the Safari Zone and Meteor Cave for one final battle. Trainer Hill is also pretty fun if you want a milder challenge.
FR/LG are the best iterations of Kanto. While you are locked to the original 151 before becoming champion you are fully expected to add Johto Pokemon to your team in the post game for the E4 rematch as well as the trainer tower. In retrospect it definitely bridges the gap for Johto, even if not every Johto Pokemon is available in Sevii. Sevii itself is a bit novel because there hasn't been something done to its scale gameplay wise. The closest thing to compare it to would probably be the Isle of Armor if the Isle of Armor had other trainers to battle that posed a threat. It also has never shown up in any other game which adds to its strange mysteriousness.
The GameCube games are a nice change of pace for the series as you are generally locked into using certain Pokemon. For even more style points any Pokemon you catch in either of these two games is unquestionably transferable to the GBA games if they are not shadow Pokemon. There's a battle mode in Colosseum that is similar to Pokemon Stadium and the teams there do not fuck around.
I'm too lazy to post cons but keep in mind a lot of them are really subjective, more so than my statements above.
