What are passwords in the 3DS version of SSF4 for

I have not played SSF4 on the 3DS, but I can provide some general Street Fighter 4 tips:

1. Start by sticking to a single character and becoming familiar with all their attack moves and supers. It doesn't matter what 'tier' your chosen character is, familiarity is more important. Learn the range of the normal attacks, specials, and ultras. Test this out with all three power levels (jab, medium, and fierce).
2. Be defensive. Typically, the CPU is pretty bad at being defensive, even going up against the most difficult level CPU, you can typically force them to commit into an attack or become airborne, leaving them wide open for a counter.
3. Do not overuse special moves. Quick jabs and pokes can often be very effective, and may knock characters out of their special attack (crouch + jab vs blanka's roll, for instance).
4. The air is not your friend. Do not over jump in an attempt to reach the opponent, when you are in the air you cannot block and can easily be hit.
5. Your super bar is not just for supers. Often, a charged up special (by hitting 2 out of the 3 punch or kick buttons to perform the move), will allow you to completely overpower the opponent's special move. Certain characters, such as Blanka's roll, will allow him to completely blow through a hadouken.
6. Don't forget that you can throw. If the enemy is right next to you, throw them for some damage.
7. Learn your counters, certain special moves are great counters for anyone who's being overly aggressive. For instance, the shoruyken is great move to pull off just as you are getting up if you know the enemy is about to perform an attack.
8. As you become more familiar with your character, you can start learning the combo moves that they have. These lead very well from normal jabs and pokes that you perform. For instance, if your jab just happens to hit them when they are not blocking, you can follow up with a second jab and then a special if you time it right. Long combo chains will come as second nature to you over time as you become more familiar with your character.
9. Have fun, if you can't win, consider turning down the difficulty level, turn it back up as you become more skilled.

Most of these tips will let you master fighting the computer (SF4 versus is another matter ;).

SC = Super Combo meter (max 4 bars); UC = Ultra Combo meter (max 2 bars).

You will get variants for each figure. Some will have SC and UC bars filled. If you have a figurine with one of these, it will have already one or more SC/UC parts ready to use right at the start of a StreetPass match.

Only Power, Defense, and Speed can all be altered for a given figure, up to 300.