Do possessive pronouns receive the "-n" and "-j" endings?

If I want to say, "Your friends are good." Should that be, "ViaJ amikoj estas bonaj," or simply "Via amikoj estas bonaj?"

And if something is in the accusative case,

"I ate your kangaroo," should that be "Mi mangxis viaN kanguruon?"

I was told the definite article "La" never receives endings, so I'm just wondering if possessive pronouns do or not.

Yes, they do.

Mi manĝis vian kanguruon.
Mi manĝis ĉiujn viajn kanguruojn.

As a general rule:
o-words (substantives) can receive -j, -n, -jn
a-words (adjectives) can receive -j, -n, -jn
e-words (adverbs) can receive -n but not -j
personal pronouns (mi, ci, li, ŝi, ĝi, ni, vi, ili) can receive -n but not -j

nornen:Yes, they do.

Mi manĝis vian kanguruon.
Mi manĝis ĉiujn viajn kanguruojn.

As a general rule:
o-words (substantives) can receive -j, -n, -jn
a-words (adjectives) can receive -j, -n, -jn
e-words (adverbs) can receive -n but not -j
personal pronouns (mi, ci, li, ŝi, ĝi, ni, vi, ili) can receive -n but not -j

and don't forget the -iu series of the correlatives (kiu, cxiu, etc).