Save your game before doing this trick. Make sure you have a lot of points to spend, then go to the card shop. Buy all packs in the shop for the rare card you want (for example, Liquid Snake, Genola, Solid Snake, etc.). If you do not obtain any cards you want, go to options then return to the title screen. Reload your game and do the same thing until you get the desired card.
Play as Teliko
Successfully complete the Residential Zone mission to unlock Teliko.
Raiden card
Successfully complete the game two times to unlock the Raiden card.
Solid Snake (MG) card
Successfully complete the game to unlock the Solid Snake (MG) card.
Special scenes
When you start for the first time you will probably will not get the special scenes from Metal Gear Solid, Metal Gear Solid 2, and Metal Gear Solid 3. To do this, have all or most character cards. For example, start a new file after getting to the Leone battle. With the new file, you must get all the character cards ,or whenever you get on, again. When you use you should have a video sequence from when Snake met or fought the character on the card. Note: Not all character cards will have special scenes.
Unlock Link Battle
After clearing stage 6, Link Battle will be available by going into Options from Intermission.