Judging question: mulligan issues

[Lucario EX]

Just a couple hypothetical questions I'd like opinions on, because it seems like something that would vary a lot, and I've never seen it brought up before.

Situation A:
Both players are setting up. Player A announces a mulligan, and shuffles his hand back into his deck, without showing it to his opponent, before Player B can stop him. Player B calls a judge. What is, in your opinion, the correct penalty and/or fix?

Player A could have simply not known he had to show his hand to his opponent; a lot of noobs seem to not remember that. Or, he could have gotten an Unown G and 6 energy, and faked a mulligan to get a new hand.

Situation B:

Again, start of the game. Player A calls a mulligan, briefly reveals his hand to his opponent. Then, after he's shuffled, he remembers that he had a fossil or an SP version of an evolution, and that it would count as a Basic. Player A calls a judge. Player B claims that he did not see the cards long enough to tell what they were. What happens this time?

[waynegg]

on either as a first time offense:

Juniors and inexperienced players- issue a caution (tier 1) for Game play error minor
I would relate it to this under 7.1.1:

• Inadvertently revealing the top card of your deck, or one of your Prize Cards.

Experienced players- issue a prize card penalty (tier 2) for game play error major
I would relate it to this under 7.1.2:

• Shuffling your deck mid‐game without the use of a card effect.

I would have to escalate to the tier 2 with the experienced player because it gave an unfair advantage and they are expected to know the rules.

[corrupti0n]

The fossil doesn't have to be played as a basic. In the hand its still a trainer so he gets to mulligan.

[ShuckleLVX]

Originally Posted by corrupti0n

The fossil doesn't have to be played as a basic. In the hand its still a trainer so he gets to mulligan.

This is incorrect. If you have a fossil in your hand at the beginning, not only may you play it as a basic, you MUST if it is your only viable basic.

Q. If you have basic and fossil Pokémon in your hand at startup, can you choose to play only the fossils and not the basic?
A. Yes. You can play "just" the Fossil Trainer cards, if you have fossils and a basic. If your opening hand has Fossil Trainers only, but no Basic Pokémon cards, you must choose a Fossil Trainer to place active. (Oct 16, 2003 PUI Rules Team; Jul 27, 2006 PUI Rules Team)

[Yoshi-]

I dont know about the first one, but I doubt anything else then a gameloss would be just for the first one.
If a player just shuffles his hand into his deck the game is broken, doesnt matter if he announced mulligan or not, since he never showed it the game becomes unreparable IMO.