I know they will likely not read it but when sleeping I found these to be added (with addition of other suggestions posted before):
- Rod Reiss Titan (giant dude that's twice as big as Colossal Titan (120 m) and crawls a lot, exposing his internal organs and sheds off his face to half)
- Thunder Spear
- Anti-Titan armaments (either artilleries or firearms, other firearms may kill Titans)
- Founding Titan (various forms from Ymir Fritz to Eren Yeager)
- Female Titan's inheritor should crystallize once they exited their Titan
- Wall Titan
- Anti-Personnel ODM Gear
- Abnormal Titans, a kind of pure Titans but quadrupedal or some kind of that, just like in the Anime's earlier episodes