Neotanks in Advance Wars 2

Why can’t I build Neotanks with other armies than Orange Star? On Great Sea Battle, if you need to know, but also the others.
Answer #1
I have not played part 2, sorry. But do you know about newer versions, which i can play on pc?
I read there is one for DS?
Answer #2
Yes and yes.
Answer #3
Ok, thanks man.