 There are 23 old Mystery Gift Pokemon events that you can still get right now in your copy of Pokemon Black and White. To access, grab your DS and go into your internet settings and change settings. Scroll across to DNS and say no to auto-obtain then click into detailed setup. Change the primary DNS to the following 167.086.108.126. Click ok, save your settings and boot into Pokemon Black or White. At the title screen go into Mystery Gift, Received Gift and Choose Get via Nintendo WFC. Once you have done this you will receive one of the 23 possible old mystery gifts at random. A full list of the events will be in the description. After this go into game and visit any Pokemon Center, speak to this NPC and collect your prize. You can then move these gift Pokemon into scholar and violet through Pokemon Home by trading them up using Pokemon Transporter and buying to show off some of these exclusive shiny event Pokemon from over 10 years ago.