If I may add some comments…
(note that I’m not a native speaker nor a professional translator, so take each with a pinch of salt)
私をフォローしてください I think is more commonly used than 追加してください
“for sale”
販売
I would say こちらは販売中です, I think it sounds more proper
“sorry, not for trade/sale”
申し訳ございません。
That’s a relatively formal way to apologise, but doesn’t actually say anything about trading/selling. I would say すみませんが、こちらは非売品です or if you want to be extra polite then 申し訳ございませんが、こちらは非売品です。
Extra extra polite? Then
誠に申し訳ございませんが、こちらは非売品でございます。
“want to play? (TCG)”
遊びたい?(TCG)
This is a very informal way of asking. I would say something like
遊びましょうか? or (TCG)を一緒にやりませんか?
Seeing as the politest form possible was asked… you could even say…
お遊びになりますでしょうか?
Just keep in mind if you don’t look like a native Japanese speaker you will be given a pass if you’re a bit off. If your goal is to print this on a sign or something, you can also rely heavy on images since they are a universal language
@pkmnflyingmaster
^ I mean, this translates properly wherever you are