You can read more about the .gpf patch format at this link, but here are my notes:
https://gist.github.com/wilm0x42/2382af4e200a6bb076c91c56813aba54

--------------------------------------------------------------------------------
RSBE01.gpf is made up of 14 patches

1.
destination address = 800044C0
patchsize = 00000EA0
data = (too big to write out. stored in patch1.bin)

2.
destination address = 80215FEC
patchsize = 00000004
data = 4BDEF07D

3.
destination address = 8021619C
patchsize =  00000004
data = 4BDEEBE5

4. 
destination address = 802160C0
patch size = 00000004
data = 4BDEED01

5. 
destination address = 802161B4
patch size = 00000004
data = 4BDEEC45

6.
destination address = 80216098
patch size = 00000004
data = 4BDEEDF1

7. 
destination address = 802162C4
patch size = 00000004
data = 4BDEEBF5

8.
destination address = 802162C8
patch size = 00000004
data = 48000078

9.
destination address = 8021556C
patchsize = 00000004
data = 4BDEF815

10.
destination address = 80228874
patchsize = 00000004
data = 2C000001

11.
destination address = 802288C4
patchsize = 00000004
data = 4BDDC889

12.
destination address = 80228A00
patchsize = 00000004
data = 60000000

13.
destination address = 802289C8
patchsize = 00000004
data = 60000000

14.
destination address = 8021601C
patchsize = 00000004
data = 41820078
=================================
It looks like memory can be patched with Riivolution
Riivolution patches can be patched to an ISO
There's a NSMBW and SSBB ISO patcher, looks like memory can be patched directly with xml files (NewerSMBW.xml)
Looking in ISO patcher .bat file, the patching is done by a call to Wiimms ISO tools dolpatcher (https://wit.wiimm.de/wit/cmd-dolpatch.html)
Ok cool I'll just write an xml file and patch the main.dol (patch.xml)
Command I'm using in linux for WIT patching:
wit dolpatch main.dol xml=patch.xml --source patches
ISO is rebuilt, time to try it with CFG USBloader so I can load off SD card.
No GC support and crashes
Still looking into why it's crashing 
Aaaaand I'm out of time maybe someone else can figure it out
Maybe it has something to do with sections? SSBB ISO builder creates a new data and text section




