Dictionaries have 「たくさん」 listed as being either a noun or 形容動詞。Googling "たくさんな" returns only 190,000 hits; none of the top 20 pages are professional websites. Rather, they are only blogs.
My impression is that, practically speaking, 「たくさん」 is used only as a noun? For some idiosyncratic reason, it's also listed as 形容動詞? Can anyone shed some light as to what's going on? Is this issue related to the meaning of 形容動詞、or just about that the word, 「たくさん」, is exceptional。?