Sorry for the late reply I don't go on here too often. So each egg is different and when traded to another game or if you change the Trainer ID and Secret ID on the save they all have a 1 in 8192 chance to be shiny. When game developers tried to shiny lock Manaphy they made an error where it could only be shiny locked on the game that received the egg. I've been actually doing this hunt myself on and off since January this year and I'm about 7.5k egg hatches. The original method for hunting Manaphy is usually four eggs because people buy 4 separate Pokemon Ranger cartridges and only get one egg on each cartridge without backing up the save prior to sending the Manaphy over and doesn't actually help get shiny Manaphy easily. This method makes Manaphy like a normal 8192 egg hunt, it basically removes the time restriction that is placed on making a new save file after every 4 egg hatches. When on a new game save or with the TID/SID changed it basically removes that restriction or the shiny lock per say because Manaphy was never meant to be shiny it was like Jirachi in Generation III with Pokemon Channel and Colosseum Bonus Disk it was a failed shiny lock. I hope this helps. Easiest way of putting it Trainer ID: 61633 Secret ID: 06763 this is the only game save these Manaphy's are shiny locked on. All Manaphy's have their own PID, Natures and everything so all of them can have a chance of being shiny on a new game save, they all have a 1 in 8192 chance. This method basically just removes having to start a new save after every 4 eggs, this method means you only need a new save after every 545 eggs. Hope this helps and good luck to everyone hunting for a shiny Manaphy. Also if people are wondering why there are so many if you only get 1 egg per file, if you use Checkpoint on homebrew 3ds you can backup the Ranger Game Cartridge and Pokemon Cartridge before receiving them then restore the save and keep farming new Manaphy eggs. All eggs are 100% legit and legal through Pokemon Bank and Home.
This method is a grey area in Pokemon as they are 100% legal eggs. It depends on the person who's hunting it because it's no different event Pokemon in Gen III-IV events where it's nearly impossible to access the original events unless you buy an event cartridge that wasn't for resale. I respect anyone who likes to take the harder route. One Twitch streamer who is one of my favourite streamers on Twitch has been hunting Manaphy for 4 years through the traditional method. I created this method for myself originally and thought I would share this method to allow a new way to hunt for a shiny Manaphy without the time restriction that the traditional route has but also to help people have a chance to obtain their own shiny Manaphy prior to the day when Pokemon Bank shuts down. Good luck to anyone hunting and wish everyone luck on their Manaphy shiny hunts.