Some clone headcanons:
They don’t consider themselves Mandalorian and they do not speak Mando’a (except maybe to swear) (I feel like swearing in a language you otherwise don’t speak would be common in GFFA).
Sure, some of their trainers were Mando, but there’s no way a few dozen people trained millions of clones. Most of the training had to have been automated: flash learning, droids, etc.
Squad =/= batch. Echo and Fives wanted to transfer out of Domino Squad when they were on the verge of failing their training and if we assume that batch = group of clones that were decanted and raised together, then that makes no sense.
(The Bad Batch is the exception to the rule, probably because they’re experimental. I imagine that keeping the batch together as a squad is part of the experiment)
Squads were put together based on aptitude tests. You want a well-rounded group with various abilities and talents so they would be pulled from various batches.
Clones weren’t decommissioned for cosmetic differences and if they were then how can you explain Rex? He’s a first gen clone; if anyone would have been decommed for not looking exactly like Jango, it would have been him.
(The Kaminoans are master cloners. They wouldn’t scrap a clone just because of phenotypical differences, especially not something like hair color that can take years for them to even be able to tell that it’s different)
Clones are not decommed for being injured. There’s an entire episode in season one about Grievous trying to destroy a medical station full of injured clones, FFS. We see rows and rows of bacta tanks full of clones. Think about it pragmatically: it’s easier, faster, and cheaper to heal someone than to grow and train an entire new person.
The named commanders we see in the show weren’t in batches or squads together. Just looking at the numbers, there had to have been at least several dozen commanders and there’s no evidence that they even know each other most of the time.
Rex and Cody didn’t know each other on Kamino and only met when they were both assigned to the 212th under Kenobi and Skywalker. Even though they didn’t serve together for very long before Skywalker got his own command and took Rex with him, they bonded for life.
Omega was created at the same time as Boba and the Kaminoans let Jango choose which one he wanted and kept the spare hidden away in Nala Se’s private lab as a back up.
