Yo, to everyone who is getting the
"xdelta3: target window checksum mismatch: XD3_INVALID_INPUT" error when dragging their vanilla NTSC .iso/.gcm onto the .bat file, I think I figured out some information that might help you. So although you may be using an unmodified .iso/.gcm which works normally, that doesn't necessarily mean that the .iso/.gcm you have is the version the xdelta patcher is looking for. The checksums differ between versions ie: NTSC v1.00 of melee has different checksums than NTSC v1.02 and PAL has different checksums than NTSC.
BUT, if your melee .iso/.gcm isn't
perfect the patcher flips out. It's essentially the same as if you threw in the incorrect version of melee and the patcher won't have the correct checksums to alter in order to mod your game.
You can check your checksums by doing the following:
1. Open up dolphin
2. right click>properties>info
3. click "compute" next to the MD5 Checksum box
You should then receive a long string of letters and numbers. According to
this post, the values for the different NTSC values are as follows:
099774a4a248ceacde95523e7cd42236 - My Impure NTSC Version 1.02 (.iso)
58d4dba5d0f26b8a8d3f0b2d71816e6c - My Pure NTSC Version 1.02 (.gcm)
3a62f8d10fd210d4928ad37e3816e33c - NTSC Version 1.00 (.iso)
67136bd167b471e0ad72e98d10cf4356 - NTSC Version 1.01 (.iso)
0e63d4223b01d9aba596259dc155a174 - NTSC Version 1.02 (.iso) <--- This is the one you want!
Allegedly, every pure NTSC Version 1.02 checksum should match the above Strings your training mode patch is failing because your .iso is not
perfect. This may be counterintuitive to those of you, like myself, who have previously installed the 20xx training pack since 20xx patches fine to this same .iso. I believe this is because of the way that 20xx patches, which uses root files and a rebuilder instead of xdelta.
Sidenote: I was writing this as I was checking my new working version's checksum and I thought for sure it would match the aforementioned post, but that was not the case. So my best guess is that either unmodified .ISOs and unmodified .GCMs have different checksums or some differentiation in checksum values are permitted and the cases where the mod fails to patch, the checksum values have changed too much.
As far as I've found, the only solution is to obtain a pure Melee NTSC v1.02 .iso. The optimal way to do this is to obtain the .iso from your physical copy of the game. With a shiny, new melee .iso/.gcm that is pure, the patcher should be able to successfully patch the mod to the new .iso/.gcm. If you see that your new .iso/.gcm has a different checksum string, this is a good sign. You should notice that your patching process also takes longer as well. Additionally, the mod should be the same size (1.36GB) as vanilla melee and the training mode .iso should now have a banner.
Take everything I've said with a grain of salt because I am relatively inexperienced with modding melee (though I'd love to work on a mod one day) besides installing this and 20xx. Hopefully this helps someone because this issue could easily be confused with using a modded .iso and is a little difficult to diagnose. I'll try to help out if anyone is having troubles after trying this ^v^. Shoutouts to UnclePunch for making a rad mod in the first place and being a champ and helping out with people who are having trouble installing it. Also, sorry everyone for the wall of text lol.
TL;DR: If you are using a vanilla copy of melee NTSC v1.02 that still fails with the "xdelta3: target window checksum mismatch: XD3_INVALID_INPUT" error, your .iso/.gcm isn't
perfect, obtain a pure copy that hasn't been altered and try patching again.