Pokemon GBC and GBA RTC patches with Rom Hacks?

[crazyseandx]

So, I was looking through some files, and saw an old ROM Hack of Crystal I tried to play on my PSP. The problem was that the in-game clock went bonkers(likely due to using save states), and I initially thought it was the game itself. Technically, yes, but regardless, I'm curious if RTC patches can actually be used on existing ROM Hacks such as the one in question, being Pokemon Crystal Emu Edition. Anyone know if that's possible, or will it bug up the game?

 

[FAST6191]

Depending upon what is done the clock may still have some fun with savestates.

Anyway in general ROM hacking trying to stack patches one on top of the other typically sees three problems

1) For things like xdelta then they have input verification to try to make sure the correct file is being patched. If you hack it with something else first then it will appear to be a different file and thus you have to disable that. Most GB/GBC and GBA stuff will be IPS which does not have this feature and thus problem.
2) It will try to work on the same aspect of the game and cause a problem, or have one thing be ineffective as a result. Some hacks will include a RTC patch and trying to patch on top of that might see something like this happen.
3) Both patches will try to use the same bit of "free" space in the game for their extra data and overwrite the other's extra data potentially causing all sorts of fun and games. RTC hacks should not need much extra data but they could still need some.

1) is usually solved by telling it to ignore input/source verification.
2) and 3) you can investigate as a hacker but most won't. There are some light tools that will try to detect when things will overwrite the same area but they are of limited use. Easiest thing to do here really is test it out yourself. Occasionally order of patching can make a difference, indeed in some cases a certain order is a requirement.