As far as my own experience relates to this issue, I have a set of #17-102 base set cards that all came from the same box
You can use the r/PokemonMisprints community to see if its an error or a fake, or go with CGC, one of the best Pokmon grading services for error cards
Partner (You can have two commanders if both have partner.) If your Commander deck has two commanders, you can only include cards whose own color identities are also found in your commanders' combined color identities
Interesting tidbit: Many of the Chinese Pokemon pogs have different attack names from the English ones
Sometimes thats what you need in aggressive decks, at least for 1v1 games
Fakers don't have to fool everyone, they just have to sell their product and get away with it - so we test for the silliest mistakes first, because they're more common than you'd think