Can you give more details about what you are trying to do? There are hundreds of reasons why it could be illegal.
First I suggest not to try creating things from scratch. Use the Encounter or Mystery Gift databases instead.
If it's an event that was released after the latest PKHeX release on 23/05/11, it will be shown illegal until the next release.,
The last byte of the PID is the issue. It has to be below the gender threshold.
Snivy has a male/female ratio of 7:1, so it has a gender threshold of 31. If the last byte is 31 or greater, Snivy should be male, else female. Now your Snivy's PID is 11FB33F3. Take the last byte (F3), converted from hex to decimal that's 243.
Everything from 0 to 30 would be fine. So if you take 30 (1E in hex), the valid PID for Snivy would be 11FB331E,
You can check this for more detailed info about gender PID relations https://bulbapedia.bulbagarden.net/wiki/Personality_value#Gender
You really should consider upgrading to a modern 64 bit Windows. The reason our save doesn't open on A-Save is that mGBA added RTC information to the end of the save. You could use a Hex editor and remove the last 16 bytes from your file, that should make it work again.
Just use PKHeX instead.
ROM hacks are not supported by PKHeX, they may or may not work depending on what has been changes.
If you want to edit the save of your ROM hack you should contact its author. Maybe they can provide you cheat codes, a modified version of PKHeX or any other tool.
First you should update your PKHeX, yours is from over a year ago, latest is 20230406.
After you modify some properties on the left, you need to set the Pokemon back into the slots on the right.
Wondercards use console date and you can freely change it on your 3DS. So there is nothing wrong with a Pumpkaboo from 2003. Whoever contributed this fils probably just had a wrong date set.
You can change it after redemption, it won't affect legality.
I'm not sure if there were any restrictions about which combinations of TID/SID were actually possible to get. You might have to consider that.
But besides that there's no way to tell if the Pokemon comes from a save with an altered TID/SID.
Exactly. Uninstal, rebuild the CIA using the latest version of NSUI, then install that.
I never really used NSUI, so I can't tell you how to get the proper 128kB, you might find more help on Gbatemp.
https://gbatemp.net/threads/discussion-new-super-ultimate-injector-nsui.500376/
Your save is 64kB, a proper save file would be 128kB. While this still works on some emulators, you will run into issues once you finished the E4.
VC injects can properly create 128kB save if they are configured correctly. You should really look into that before continuing to play.
I fixed your save size to be able to load in PKHeX, but you need to fix your game before you can use it.
0004000000F55B00.gbavc.sav
Do you have any older backup of your save file?
Unfortunately after completing the E4 the game attempted to store your Hall of Fame data. Usually this is at the end of the save file, beyond the 64kB. Since your file had no space to store it, the game overwrote save block 2 and 3 instead to store the data there. I got the save to load again, however your whole game progress is lost (you don't even have the Pokedex or badges...), because flags, variables and game stats are all saved in block 2. Your Pokemon should still all be there though.
I can only recover the two missing blocks from an older backup, if you have one.
0004000000E7D700fixed.gbavc.sav
You are using the latest stable release which is from February 27, this issue has been fixed on March 11.
Either wait for the next stable release or use the Dev build.
There is .EV_HP=, .EV_ATK=, .EV_DEF=, .EV_SPA=, .EV_SPD=, and .EV_SPE= as well as .IV_HP=, .IV_ATK=, .IV_DEF=, .IV_SPA=, .IV_SPD=, and .IV_SPE=, use those?