Try the GTS trick.
Chat with our AI personalities
It is impossible to obtain a Porygon2 without trading. You can get a Porygon and trade it with an Up-Grade or you can get a Porygon2 from the GTS but there is no way to get Porygon2 without trading.
That's impossible.
No. The only way to move Pokemon from Platinum is through a trade. 1 for 1.
The Trophy Garden is the only place to get Ditto in Pokemon Platinum, without trading or cheating of course.
Then you're only hope is trading for a Charmander.