If you have to ask me on what would be relatively feasible in the hacking world, it'd be a 'feature-complete' version of Soul Blade that'd be brilliant to play around with, featuring stuff with varying degrees of complexity such as:
• Having All 11 Unused Characters Playable
►►► From Standard to Mabochie, Bangu and Diver going at it - they're just frilly little extras that wouldn't be too terribly out of place to be implemented.
• Expanding the Ring Size options
►►► Original size options are 8m minimum, 22m maximum - I propose changing it to 4m min, 50m max.
• Expanding the Life Bar options
►►► Original options are 90% min, 130% max - I propose changing it to 50% min, 300% max.
• Expanding the Battle Time options
►►► You know the drill - OG time min is 30 seconds up to 50 with infinite time as the usual option. Here, I propose 10-second increments from 30 up to 90, including 99 as the final option (before infinite time, at least).
• Select the Same Character Multiple Times in Team Battle Mode
►►► The game originally only lets you have one of each character in the mode, rather than duplicates. All I ask is that restriction be removed.
And after that, it's just the basic stuff done in case the memory card can't read a save off the original game:
• Standard Secret Characters Playable
• All Weapons Unlocked
Now, sure, it's a big ask - but I assume, since we already have GameShark codes for some of these, would it be too difficult to implement on an actual ROM Hack?
I wouldn't know - I've got no skill and all the ideas, as the thread states!