I was in Australia from 2009-2015 and overstayed for about 2 years and went back to my country voluntarily-I was not deported. Currently my wife is in Canada on a study permit and I want to accompany her. Please help me how can I justify my overstay such that it does not affect my spousal visa application?
Wow overstay of 2 years looks fishy, however personally I believe once you and wife are legally married, it shouldn't be a problem provided you can get a POLICE CLEARANCE CERTIFICATE from Australia, I think this is the only document that can make things sane regardless of whatever explanation you give. But with a clearance or positive police report I believe whatever your explanation would be is fine.
I mean most Aussie visas are given online so it could be that you were on a bridging visa of which you did not know was due. Or was awaiting for visa which was later refused I guess. Anyways however it is I think only a clear record can make this look easy for u to lie or be honest.