The native Japanese for "good" is usually translated to よい(yoi) or its sound variant いい(ii or yy ), which is more commonly used in speaking while the word for "bad" is usually translated to わるい(warui) or だめ (ダメ) (dame). But the language is not so simple, especially the words which are quite frequently used like these words.
1. よい(yoi) いい(ii), わるい(warui) are adjective while だめ (ダメ) (dame) is adjective and noun. All of them ate native Japanese even they sometimes take Chinese characters like below.
よい(yoi) － 良い
いい(ii,yy) － seldom takes the Chinese character of 良.
わるい(warui) －悪い
だめ (ダメ) (dame) － 駄目、打目
2. The meanings and usages of よい(yoi) and its sound variant いい(ii) are not the same although mostly interchangeable. I will take いい(ii) here as it is more familiar with me and I use mostly use いい(ii) and use よい(yoi) in some special occasions.
Some exceptions even in speaking
a) You must use よい(yoi) is when you say "if it were good" or "if it were OK with you", which should be "もしよければ(mohi yokereba)", never say "もしいければ(mohi ikereba)".
b) When the negative or negation word "(nai) for "not" is followed you must use よい(yoi). よくない(yoku-nai), never say いくない(ikunai).
4. わるい(warui) is usually used for "bad" as the apposite meaning of いい(ii) of " good".
5. わるい(warui) is also usually used for "wrong" as the apposite meanings of いい(ii) of "right".
6. いい(ii) is not a pure adjective in case of the meaning of "good" but almost always means "brtter than the average" . Likewise わるい(warui) is not a pure adjective in case of the meaning of "bad" but almost always means "worse than the average". These are adjective nature so they can be used in comparative form like もっといい (motto ii) (better) もっとわるい (motto warui) (worse).
7. わるい(warui) is often replaced by the negation of いい(ii) - よくない(yoku-nai) unless "really bad" or "seriously bad", where わるい(warui) is used. In Chinese the word for bad is almost always the negation of "good (好)－"not good (不好)" is used.
8. いい(ii) has the meaning of "may" or "OK" like してもいい (shite-mo-ii) (you may do). The opposite "may not" or "not OK" is not わるい(warui) but だめ (ダメ) (dame) like してはだめ (shite-wa-dame) (you may not do).
9. だめ (ダメ) (dame) is not an adjective so has no comparative use. You cannot say もっと だめ (ダメ) (motto dame).
9. だめ (ダメ) (dame) is used as "to give up" like もうだめ (mou dame) (I will give up).
10. だめ (ダメ) (dame) is also used as "no use" like このペンはだめだ (kono pen wa dame-da) (This pen is no use or This pen is not good for use)
11. Special uses of わるい(warui)
a) わるい (warui) means "Sorry." , "I apologize." Sometimes used with ね (ne) at the end わるいね(warui-ne)
b) わるいね (warui-ne) means "Thank you." as well in certain cases
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