zhèxiē wánjù dōu wánhǎo.

Because 些 already does that job here.

In Mandarin, demonstratives like 这 and 那 normally need a measure word before a noun:

• 这个玩具 = this toy
• 那个玩具 = that toy

But 这些 and 那些 are special forms meaning these and those, and 些 itself indicates an indefinite plural set. So you say:

• 这些玩具 = these toys
• 那些玩具 = those toys

You do not say 这几个玩具 unless you specifically mean these several toys / these few toys.

The noun 玩具 itself does not change form. Mandarin nouns usually do not have different singular and plural endings like English toy / toys.

The plural meaning comes from 这些, which already tells you there is more than one toy:

• 这个玩具 = this toy
• 这些玩具 = these toys

So 玩具 stays the same, and the plural idea is shown by the words around it.

都 means all.

In 这些玩具都完好, it shows that the statement applies to the whole group of toys:

• 这些玩具完好 = these toys are intact / these toys are in good condition
• 这些玩具都完好 = these toys are all intact

So 都 emphasizes that every toy in the group has that quality.

Because Chinese adverbs usually come before the verb or adjective they modify.

Here, 都 modifies the predicate 完好, so it appears before it:

• 这些玩具 都 完好

A useful way to think about it is:

• topic/subject: 这些玩具
• adverb: 都
• predicate: 完好

This pattern is very common in Mandarin:

• 他们都很忙。 = They are all busy.
• 这些书都很有意思。 = These books are all interesting.

Because 完好 is an adjective-like predicate, and Mandarin normally does not use 是 before adjectives.

In English, we say The toys are intact.
In Mandarin, adjectives can directly function as the predicate:

• 玩具完好。 = The toys are intact.

By contrast, 是 is mainly used to connect nouns or noun phrases:

• 他是老师。 = He is a teacher.

So:

• 这些玩具都完好。 = correct
• 这些玩具都是完好。 = not natural

Because 很 is not always required.

Learners are often taught sentences like:

• 他很好。 = He is fine / good.

That can make it seem like adjectives always need 很, but that is not true. Adverbs such as 都, 也, 非常, 真, 还, and others can appear before the adjective instead.

In this sentence, 都 already comes before 完好, so 很 is unnecessary:

• 这些玩具都完好。

Also, 完好 is a somewhat formal, descriptive word, and a bare adjective after 都 sounds natural here.

Not exactly.

完好 means something like:

• intact
• undamaged
• in perfect condition
• complete and not broken

It is more specific than 好.

Compare:

• 好 = good, fine, okay
• 完好 = completely undamaged / intact

So if you say 这些玩具都完好, you are not just saying the toys are good in a general sense. You are saying they are all still whole and undamaged.

It is understandable and correct, but it does sound a bit more formal or report-like than everyday speech.

For example, after checking items, a person might say:

• 这些玩具都完好。 = These toys are all intact.

In casual conversation, people might also say:

• 这些玩具都没坏。 = These toys aren’t broken.
• 这些玩具都还是好的。 = These toys are all still good.
• 这些玩具都好好的。 = These toys are all perfectly fine.

So 完好 is natural, but slightly more formal and precise.

The structure is:

• 这些玩具 = subject/topic, these toys
• 都 = adverb, all
• 完好 = predicate adjective, intact / in good condition

So the overall pattern is:

subject + 都 + adjective

This is a common pattern when describing a whole group:

• 学生都来了。 = The students have all come.
• 苹果都红了。 = The apples have all turned red.
• 这些玩具都完好。 = These toys are all intact.

Yes. 全都 means all too, and it can add emphasis.

• 这些玩具都完好。
• 这些玩具全都完好。

Both are correct.
全都 can sound a little stronger, like every single one of them is intact.

The tones are:

• 这 (zhè) — 4th tone
• 些 (xiē) — 1st tone
• 玩 (wán) — 2nd tone
• 具 (jù) — 4th tone
• 都 (dōu) — 1st tone
• 完 (wán) — 2nd tone
• 好 (hǎo) — 3rd tone

So the full pronunciation is:

zhèxiē wánjù dōu wánhǎo

A learner tip: the final hǎo is a full 3rd tone here. Since it is at the end of the phrase, you can give it a clear low-dipping contour.