So I used DKCRE to replace the first gnawty in the game to Very Gnawty (the boss). I decided to fool around with the game, and discovered some very interesting things...
Note: I will refer to both DK and Diddy since nothing is changed by who does what. Also, I will refer to Very Gnawty as VG because I don't feel like typing that over and over again.The first thing I noticed was that a DK barrel appears at exactly DK's height when you approach VG. I would guess that this is because the barrel spawn is scripted together with the VG's spawn, therefore it appears at the exact same time. I would assume this is correct for the other bosses too.
Second, I found that VG does not move, instead he does his jump animation in place. If DK jumps on him, he will bounce as if off of an enemy. This allows for the accumulation of "infinite" lives, so to speak. This is significantly different from the actual boss fight, since there VG will knock DK off when he jumps on him. Rolling into VG bounces you back as if it were rolling into an Army. However, walking/running into VG hurts you, as his hitbox is still active. If you throw a barrel at VG, it doesn't seem to hurt him but he does face the direction it hit him from. If you ride a steel barrel into him, he will be moved a small distance but remain alive.
While testing all of this I found that the camera seems to swerve in his direction, no matter what distance you are from him. You can even finish the level, but the camera will always be showing the left side of DK. Of course, the camera does swerve to the right when to the left of VG, but it is not as noticeable or obstructive because of the small distance there exists for this effect.
If you enter any bonus or the Kong Banana Hoard and exit, VG will be moving! He will be doing very small jumps (phase 1 of the boss battle) but is still invulnerable to your jumps and barrels.
I decided to document this because of the odd nature of his behaviors when not in his natural habitat.
If this should go into the DKCRE topic, then a mod will probably move it, but I put it here since it was technically a "Rom Hack". Ok so it was moved
Edit: I have attached the ips patch (cause Roms aren't allowed, yes I actually read the rules). The stuff later in the level was for random playing around