Could I play Blaine's Quiz Show and put down Munchlax which has no attack?
No. You can only choose to put down a Pokemon that has an attack you can declare to your opponent.
Source: Unified Minds FAQ (2019-07-19), TPCi Rules Team (2019-08-01)
If I play Blaine's Quiz Show and put down "Celebi and Venusaur GX", do I win if the opponent says "Venusaur and Celebi GX" instead?
As long as they get both Pokemon of the Tag Team correct and they include the "GX" part, you shouldn't get that nit-picky about which Pokemon is billed first.
Source: TPCi Rules Team (2019-08-01)
Say I play Blaine's Quiz Show and put Giratina Prism Star down, but my opponent just says "Giratina". Do I get 4 cards?
Yes, you do. Your opponent needs to name the full name on the card.
Source: WotC Chat (2001-01-18), TPCi Rules Team (2019-08-01)