Mysterious Fossil (SS 91). Mysterious Fossil (and all Fossil cards) cannot be placed as a Pokémon during set up. Any hands with a lone Fossil must be considered mulligans.
Game type: QUICKPLAY
Game format: EX Series
Battle started between JasonKlaczynski and Primallatios!
Coin flip result: TAILS
Primallatios will start
Game setup complete
Turn 1 begins
Turn 2 begins
JasonKlaczynski drew 1 card
Attached a Fire Energy (RS 108) to Aipom.
WorldChampChuck is now a spectator of the game from JasonKlaczynski's POV
WorldChampChuck has exited spectation.
Note that the other fossils (Claw Fossil & Root Fossil) force a mulligan. Only Mysterious Fossil is treated as a Pokémon during set-up.
It is true that in 2004 you had the option to start or mulligan with a Fossil Pokémon, but this was later determined to be incorrect and revised. The rule was changed to force the starting of Fossils and eventually changed again to never allow players to start with a Fossil.
I spoke to Kyle Sucevich about this and he agrees that players should never have been allowed to start the game with a Fossil Pokémon. The rules of the game dictate this as you cannot play a Trainer card unless it is your turn. (You can’t play a Fossil through Manectric ex’s Disconnect, so why would you be able to play one during set-up?.) Common sense also would dictate this; why would you be forced to start with Mysterious Fossil, which only has 10 HP?
I’d advise to enforce this retroactive ruling for all formats. There should be no format where a player is allowed to use a Trainer card as a Pokémon during set-up.