Skill drain (?) attack monsters

What happens to monsters summoned after skill drain is on the field.

Cyber Fortress Dragon, Dark Gaia, Montage Dragon etc.





and what happens to 0 attack monsters?

Before Skill drain , fortress attack is 2000.
After skill drain, remains as 2000.

For ? atk monsters, are they affected?

ya. you blank the text so the effect got nothing. the atk is 0.

Why blank text of ? attack = attack 0?

Because the attack of (?) is defined by the effect.

But isnt that a condition of the monster like ronintoadin? If ? attack monsters effect is not applied and attack means 0, then is it that we can search it out from deck with cards like sangan? Sorry, just a clarification cause im unclear about it

? does not equal to 0. ? is undetermined.

Search cards only work for those with determined values.

It is only 0 when cards like skill drain causes them to lose the effect which determines their attack.