When this card is activated: Shuffle all "Madolche" monsters in your Graveyard into the Deck. All "Madolche" monsters on the field gain 500 ATK and DEF. If a monster(s) in your Graveyard would be returned to the Deck by the effect of a "Madolche" monster, you can add it to your hand instead.
Madolche Chateau is a great way to get rid of Madolche monsters in your graveyard in case they are stuck there. This will boost Puddingcess’ attack and defense by 800 and then another 500 because of Madolche Chateau. Plus with Madolche Ticket on the field you will be gaining lots of card advantage and field presence everytime a Madolche monster is destroyed.
Madolche Nights and Madolche Tea Break are excellent Negation cards and double as destruction when Madolche Puddingcess is on the field but can only be activated when you have no monsters in the graveyard. This is where Madolche Chateau can be useful by returning all Madolche monsters in your graveyard back to deck.
...The second effect is the ATK Gain. Which obviously won't be negated. The other two effects move cards out of the Graveyard, so will be negated. (Technically Necrovalley'd negate the Madolche monsters themselves rather than Chateau for the last effect I guess, but same result.)