The issue to my observation isn't much of the rom, i just thing is the VC itself, not all games have compatibility to it since it only was designed to play a handful of games in mind, and pokemon SPECIALLY wasn't one of them, thus the same could be said for the boktai roms as well. The VC itself lacks proper emulation and that why only very few games are on GBA VC since it does only very basic emulation, not the advance emulation you would expect like VBA.
I may be wrong in that statement but perhaps is possible to patch the rom to some degree to actually make it compatibile with VC but i doubt it and seem like just stabbing into darkness at this point. Without actually knowledge of what to do is unimportant.
Still i like to mention that i tried Super street fighter 2 Turbo Revival and there is bugs in it, all the times in time attack were set to other records other than default record of 99:99:99 even before completetion, When i got up to fight akuma in arcade mode the game glitched and crashed. This is one of the games that needed save patch from the default sram. Just means not all games work on VC. If you have problems, just report it, and move on, cause is not the rom fault. I assume only games that don't need any modifications MOSTLY the save patch to sram from eeprom or whatever are the safeest to use, as Breath of fire 1 and 2 worked fine, metroid zero mission worked which did not need mods. Donkey kong country does work but maybe need save patches so is possible that only i played some and no issues but could be if more was played.
Anyway just sharing some observations. I actually think the real reason is VC games weren't designed to handle any rom over 4MB but again, just stabbin in darkness.
