YOU SAID:

I think he’s having a brainstorm.

INTO JAPANESE

彼はすばらしい着想を起こしてと思います。

BACK INTO ENGLISH

I think he's having the excellent idea.

INTO JAPANESE

彼は優れたアイデアを持っていることと思います。

BACK INTO ENGLISH

He'd have good ideas.

INTO JAPANESE

彼は良いアイデアがあります。

BACK INTO ENGLISH

He has a good idea.

INTO JAPANESE

彼は良い考えを持っています。

BACK INTO ENGLISH

He has a good idea.