The key factor making Synchro decks tricky to pull off is that unlike fusion decks where cards can be tributed from your hand provided you have the appropriate fusion spell card, all synchro tribute cards have to be summoned to the field to be eligible
Its particularly good for nonspecific tribal decks that have multiple creature types, like Sea Creatures (Leviathan, Octopus, Serpent, etc)
Such a trade can only be proposed in the postgame after Yami Marik has been defeated, if the player has a copy they can trade away, and in the case where a god card is offered by the opponent, the opponent has said god card
Anathemancer This is Price of progress
The rest of the sets with god packs have a different classification and different booster box contents
She does a much better explanation of the sections than I do