Maybe they can only appear when connecting to your original B/W and B2/W2 games maybe? Kind of like Memory Link, in a way, so that they'll relate a little to your original character.
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I've done everything I wanted and it was more than I thought it'd be
I will leave my mark so everyone will know
I was here.
I lived, I loved
I did, I've done...
I just want you to know that I gave my all,
Did my best,
Brought someone some happiness
Left this place a little better
Just because I was here...