Reduplication in adjectival nouns is somewhat more complicated than for nouns or adjectives. The reason for this is that as we’ve learned before, whether to use na な or no の is a bit all over the place, and in addition to that, many of the phrases shown here may also have alternate uses as adverbs.
Just as before, some examples of reduplication in adjectival nouns derive from nouns, adjectives, adjectival nouns, verbs, and even onomatopoeic expressions. However, you will be disappointed that the number of reduplicated adjectival nouns is dwindling in Modern Japanese.
・From Nouns: Kazukazu [no] 数々（の）－ Numerous
・From Adjectives: Atsuatsu [no] 熱々（の） － Piping hot
・From Adjectival Nouns: Boroboro [na/no] ぼろぼろ（な・の） － Run-down
・ From Verbs: Tobitobi [na] 飛び飛び（な） － Scattered here and there
・From Onomatopoeia: Pikapika [no/na] ぴかぴか（の・な）－ Sparkling
Grammatical restraints are just as all over the place as the etymologies of these instances of reduplication. Most instances can be used as adverbs by using ni に, which is no different than the majority of adjectival nouns. However, some may only be used to the extent of ni naru になる, and so playing with each one to see how much it can be used in is necessary.
From Nouns
1. 社会に出ると数々の問題に直面する。
Shakai ni deru to kazukazu no mondai ni chokumen suru.
When you enter society, you encounter numerous problems.
2. 種々の対策を講じる。
Shuju no taisaku wo kōjiru.
To take all sorts of measures.
3. 色々な場所にポケモンが生息しています。
Iroiro na basho ni pokemon ga seisoku shite imasu.
Pokemon inhabit various places.
4. お肉は程々の味で値段も割高です。
Oniku wa hodohodo no aji de nedam mo waridaka desu.
As for the meat, the price is also fairly expensive with a moderate taste.
5. 彼は元々、結婚願望がなかった。
Kare wa motomoto, kekkon gambō ga nakatta.
He had no desire to marry from the start.
Usage Note: Motomoto 元々 may be used as an adverb without the need of any particle.
6. 元々の意味はご存じですか。
Motomoto no imi wa gozonji desu ka?
Do you know what the original meaning is?
7. 帰宅が遅くなったりしますが、営業職としては並々の残業かと思います。
Kitaku ga osoku nattari shimasu ga, eigyōshoku to shite wa naminami no zangyō ka to omoimasu.
Coming home is sometimes late or what not, but I think that’s ordinary overtime for a business job.
From Adjectives
8. ピリ辛で熱々のキムチをご飯と一緒に食べました。
Pirikara de atsuatsu no kimuchi wo gohan to issho ni tabemashita.
I ate my meal/cooked rice with spicy and piping hot kimchi.
9. 久々にカレーを作った。
Hisabisa ni karē wo tsukutta.
I made curry after a long while.
From Adjectival Nouns
10. 夫は結婚するまでぼろぼろの服を着ていました。
Otto wa kekkon suru made boroboro no fuku wo kite imashita.
My husband worse ragged clothes up until we got married.
From Verbs
11. 亮太君は彼女に息が絶え絶えになるほど熱いキスをした。
Ryōta-kun wa kanojo ni iki ga taedae ni naru hodo atsui kisu wo shita.
Ryota gave her such a warm kiss so strong it left her gasping.
12. 色とりどりに花が咲いています。
Iro toridori ni hana ga saite imasu.
Multi-colored flowers are blooming.
13. 空白が飛び飛びになっている。
Kūhaku ga tobitobi ni natte iru.
Empty spaces are scattered everywhere.
From Four Character Idioms
14. 奇々怪々な事件を鮮やかに解き明かしていく。
Kikikaikai na jiken wo azayaka ni tokiakashite iku.
I will vividly dispel bizarre cases.
Word Note: 奇々怪々 is rare and would usually be replaced with the simpler kikai 奇怪 from which it derives.
From Onomatopoeia
15. ぴかぴかの歯を取り戻しましょう。
Pikapika no ha wo torimodoshimashō.
Restore one’s sparkling teeth!
From Prefixes
16. 周辺諸国にもその影響が伝播し、諸々の事情によって崩壊していったとのことでした。
Shūhen shokoku ni mo sono eikyō ga dempa shi, moromoro no jijō ni yotte hōkai shite itta to no koto deshita.
That effect propagated to all the neighboring countries as well, which led to them collapsing under all kinds of circumstances.
17. 諸々、了解しました。
Moromoro, ryōkai shimashita.
Rodger that to everything.
Usage Note: Moromoro 諸々 may be used as an adverb without the need of any particle.