Bonus Bosses

RedEyedAbyss

I've made this thread already in the original TvTropes IJBM subforum, but I just encountered a particularly glaring example of what I find wrong with them: The DS Remake of Final Fantasy IV. There is barely any attempt to integrate them into the main storyline. For Geryon, all you do is press A on a designated location and you get "Will you face them"? (okay, there's a bit of handwaving, but that's it) Proto-Babil is just "Choose Dark Matter at the face on the moon". To their credit, at least this allows you endless rematches and Proto-Babil was pretty fun and hard, but what's the point of them existing story-wise?

In fact, I might as well give more examples.

Good implementation: Mario And Luigi: Bowser's Inside Story. It's part of a special challenge with souped-up versions of bosses you've already faced and updates as you go along in the game, so it makes sense in context. The boss himself: Bowser X, a super-hard version of the longtime archenemy of the Mario Bros. Who else is more appropriate?

Acceptable implementation: Final Fantasy V. Fearsome monsters of lore that the game warns you about beforehand, so that you know to get the hell away unless you're particularly ballsy. They're still somewhat random, but at least the fact they're sealed away explains why they haven't wreaked havoc on all worlds.

Shaky implementation: Tales of Symphonia. So the heroes are dumb enough to help some dude get some obviously evil weapons and get back to full strength so he can wreak havoc on all worlds. A major Big Lipped Alligator Moment that distracts from Mithos being the main villain. I mean, they're so focused on the angelic pretty boy that they forgot about all those other crazies running about.

I used to like the idea of bonus bosses, but now, I often wonder why they couldn't be part of the main game rather than just being some disconnected thing to appease people looking for a greater challenge.

DYRE

They can't be part of the main game because then they wouldn't be bonus bosses.  Also because then they'd have to be not so difficult so that the average player can actually beat them.

Unless you mean something else.

Stormtroper

Acceptable implementation: Final Fantasy V. Fearsome monsters of lore
that the game warns you about beforehand, so that you know to get the
hell away unless you're particularly ballsy. They're still somewhat
random, but at least the fact they're sealed away explains why they
haven't wreaked havoc on all worlds.

Ehh, you aren't warned about Omega until you get past it, for which you have to manually evade its path, and Shinryuu is a monster-in-a-box, and we don't have a reason to think they're still sealed by the end of the game (the other monsters aren't). With the rest of the post in mind, I think they're a particularly bad implementation.

RedEyedAbyss

Point. Though the sheer shock of seeing that surprising giant monster annihilate your entire party in one hit certainly stuck in my head (and initially made me avoid the rest of the chests). I guess I didn't mind their arbitrariness as much because they were encountered over the course of the game and were memorable monsters in a sense. Even though they're just palette swaps.

Bee

I prefer when bonus bosses at least have some sort of subplot to them myself, however minor.

Really, it takes almost no effort to put an NPC someplace and give them a line of dialogue to namedrop the dungeon/boss.

RedEyedAbyss

Yeah, something to sort of justify their existence. Though like I mentioned in the Tales of Symphonia example, sometimes it gets ridiculous.