Just like with every previous entry in the Megaman Battle Network/Starforce series, just because you complete the main story of Megaman Starforce 2 doesn't mean you have seen everything the game has to offer. I beat the final boss over a week ago, and I have been playing the post-game since. While this may not be the first of these post game sequences that I have played through, it has certainly turned out to be an interesting one.
Every post-game in the series has been very different from the others. Battle Network 2 had a hidden dungeon area filled with a series of secret bosses that culminated in a second ending. Battle Network 3 had an extensive mass of labyrinthine areas, several normal secret bosses, two extremely powerful special bosses, and a whole series of special challenges that culminates in a rematch against an vastly improved version of the game's final boss. Battle Network 4 had... something I never qualified to see (thanks to a severely flawed game structure). They all differ greatly, and how much I have played through these different post-game sequences varies just as much. I almost completely cleared Battle Network 2's post-game (other than unnecessary 100% chip collection), I went very far into Battle Network 3's massive post-game, but couldn't beat BassGS and never saw the Serenade Time Trials, and I never really got into it for other games. A large factor in determining how far I made it was difficulty (such as the previously mentioned difficult BassGS fight, and the similarly hard BassBX fight in BN 6), but at other times there have been other factors involved. For example, I never even really started Battle Network 5's ambitious post-game simply because it forces you to acquire close to two-thirds of all the battle chips in the game in a very short period of time. These post-game sequences are always a lot of fun because of the focus on intense difficulty and big rewards, which helps balance out the sometimes too-easy main game, but they can be uneven in execution.
Megaman Starforce 2's post-game is probably one of my favorites so far. It is longer than Starforce 1's disappointingly short post-game, but much more manageable in size than something like Battle Network 3's post game. Also, unlike some, it paces out the difficulty properly so you don't have to force your way through an extremely difficult fight (like BassGS) in order to see large sections of it. Instead, almost the entire post-game is focused on a side-plot that is introduced right after you complete the game, progresses through a rematch with a powered-up "IF" version of every boss, and culminates in an appropriately difficult battle against a totally new enemy. The actual size of the post-game special area (the Alternate Future and Trans-Dimension zones) is much larger than ever before, which helps spread out the large number of new viruses better than before, making it easier to gather every standard battle card (a typical requirement for progressing through the post-game).
One particularly good feature of the Starforce 2 post-game is the way it has organized the "challenge gates" that are typical to the series. In most previous games, you had to pass through a series of doors that can only be opened by completing certain challenges, such as S-ranking every boss, gathering every card of a certain type, or acquiring every available transformation. These doors have typically been arranged so that you need to clear every one in order to reach the end of the post-game, but Starforce 2 changes it so that almost all of them are optional. Instead of unlocking them in order to progress, you unlock them to get special prizes, such as Giga-class Cards and powerful Abilities. In addition, a lot more of them have been added, including some with an incredibly high level of difficulty (defeat every SP boss in under ten seconds?!), transforming them from bothersome obstacles into fun optional goals.
If I have a complaint about this post-game, it is that the requirements needed to progress can be a bit too vague at times. The post-game starts by giving you a clue that leads you to the key needed to enter the post-game area, but how you are supposed to actually use that key is left vague, and is in fact very counter-intuitive, even if it is easy to do by accident. Much more notably, after defeating the boss of the Trans-Dimension you are instructed to find the 6 badges in order to find "true despair", but you don't get any hints on where to find these badges. The first five are easy enough to get (gather all Standard, Mega, and Giga battle cards, beat the game, and complete the Trans-Dimension plot), and are mostly gathered in the process of getting that hint, but the sixth isn't hinted at all. In order to get that one, you need to gather the first five badges and re-challenge the final boss, who has transformed into a much more powerful foe. This is not the kind of thing that you are likely to stumble across just by exploring the game world (particularly since I originally thought you needed all six badges to even fight the improved final boss), and I only found out about it thanks to looking it up at GameFAQs. This kind of poor hinting is something where just a small addition to the game can prevent a lot of frustration for the player, and the game mostly avoided the problem, so I was rather disappointed to run across it.
Other than that, my only other complaint is that the ultimate challenge of the game, the battle against RogueSX, is put in a bad place. In order to even reach this battle, you need to collect all six badges, defeat the improved final boss again, and fight RogueSX after the credit roll. Since you can't save between the boss battle and the RogueSX battle, it means you need to win one of the hardest battles in the entire game over and over again every time you even want to challenge RogueSX. Since it took me four tries to beat the powered-up final boss, and another four in order to beat him again and challenge RogueSX (a battle I quickly lost), I simply don't have the will to keep going at it any more. The entire thing is simply too tedious to bother with.
Still, this is the first Battle Network/Starforce game where I have even seen the improved final boss, let alone beaten it and collected all of the star badges, so I feel pretty happy with the game. The entire post-game simply had a much more graceful difficulty curve and more manageable challenges than any Megaman game before it, which made it a lot more fun.