No. हाथी is a male noun and as such would remain हाथी when pluralised.
You will sometimes see the plural form written as हाथियाँ. This type of construction is only used for female nouns (eg: बिल्ली - बिल्लियाँ) so हाथियाँ is technically incorrect.
In the oblique(possessive) case, you use हाथियों but this has to be followed by a postposition like के, से, में etc. (Eg: हाथियों के पैर बड़े होते हैं )
But does it even make sense? I mean हाथी is a male gender so whether it is pluralized or in oblique case it should remain the same हाथी (same way as आदमी), shouldn't it? The only case when हाथियाँ can possibly make sense is when we talk about female elephants, though even with this sounds doubtfully to me.
You are right about the plural. हाथी is the plural of हाथी and हाथियाँ does not make any grammatical sense. Even when you are talking about female elephants, using हाथियाँ would be incorrect grammar.
But in the oblique case, masculine plural nouns with the ी ending also take the form ियों (incidentally the same as feminine plural nouns in the oblique case). So, the oblique form of plural हाथी is हाथियों. (Note: The oblique form of singular हाथी is हाथी itself)
The same is true for आदमी . Its plural is आदमी but in the oblique case, the plural becomes आदमियों.
Eg: इस दुकान में आदमियों के जूते नहीं हैं। - There are no men's shoes in this store
Oh, okay.. yes, makes sense now! I missed difference in endings ..याँ and ..यों that's why I got confused. Thank you!