Street Fighter x Tekken has an original assist system called the "Gem System." To use this system, you set your character with gems prior to battle. The gems give your character support during battle.
There are two types of gems: Boost Gems and Assist Gems. Boost Gems do such things as up your character's attack, defense and speed parameters when triggered. Assist Gems are in place throughout battle and give you things like auto throw and auto guard.
Take a look at some screens of the Gem System below.