I was just trying to make sense of this. The walled city had 2 titan powers at the start of the series when BRA attacked. They have the Coordinate and they had the power of memory manipulation.

As many people pointed out it seems like Grisha ate only one titan and was able to gain both abilities. So that leaves us with a problem

How did Grisha turn into a titan? Did he simply use a serum and then bet on being able to eat Frieda? Was he a shifter already? no matter the answer there is still a bigger problem.

How is he even human? At the very end of the chapter it says that they were sent to Utopia which is the Island the walled city is on. It also says they were given a serum to make them turn into mindless titans. So how exactly did Grisha even turn back once on the island? Maybe he was never turned into a titan but then why?

The other 7 powers are accounted for as Marley has them. Lastly it seems like in the version of history the rebels are thinking is true, it says that king Fritz left the other titans but doesn't state why. This could be why the kings inside the wall have all refused to save humanity after they inherit Fritz's memories.

As far as the powers he has now, I think he only has two, the Co-ordinate and the Memory Manipulation. I think the bottle he drank allows for shifters to be able to use their hardening abilities or at least enhances their ability to learn how to do it. We already know both Annie and Reiner can do it so I don't think it count's as a unique power, then again maybe to the extent that Reiner can do it, it does. Either way I'm pretty sure that was all that he gained from his encounter with Historia.