This category includes a dozen or so various skills and gadgets. As I already mentioned at the first page of this guide, the successive upgrades are not unlocked with upgrade points. Instead, you need to complete various activities, e.g. complete side missions connected with the Most Wanted, find Enigma's collectibles or complete the Dark Knight System requirements. The requirements to unlock each and every upgrade are listed in its description so, it is easy to find out what you need to do to obtain it.
One of the most useful upgrades here is the Free Flow Focus. Gaining access to this upgrade will allow you to achieve higher scores for combat, because it will be easier to keep the multiplier high. The same holds true for the Free Flow Power Gadgets and Critical Strike.
Many of the gadgets in this group increase the efficiency of Batman's gadgets. I recommend that you unlock, in the first place, the Sequencer - Increased Power and Sequencer - Increased Range, because having it on you is required to find some of the Enigma collectibles. Apart from that, you should also unlock the Sonic Batarang (a whole new gadget) and the Smoke - longer effectiveness.
When it comes to the remaining skills, the Shockwave is the most useful, in my opinion. This is an interesting alternative to the Gliding attack and it allows you to knock down a larger group of enemies right at the beginning of the fight.