Why yes, ReBURST is about people fusing with their Pokemon, this process is called Burst. In order to perform it you'll need to use this pocket size jewel called Burst Heart, it hasn't been shown how they are made, but they can store a Pokemon inside of them, similar to Pokeballs, but the only way of calling these Pokemon outtta their Burst Hearts is by performing Burst. After this fusion, said person will change in appearance matchign that of the Pokemon closely, gaining their powers and weaknesses as well. Weakening someone after performing performing Burst makes it more likely for the Burst Heart to break. In case this happens, the Pokemon inside of it becomes released, and may or may not stay with its owner. In order to perform Burst, one must go through rigorous training, or else they face the chance of getting hurt or even die. One person may also temporally access the inside of their Burst Heart if they focus on it enough. These jewels have an inside that differs in appearance depending on the Pokemon inside, say, as if it was their own world. Being inside here allows someone to bond with the Pokemon inside. Similar to Pokemon battles, performing Burst earns battle experience to the Pokemon inside the Burst Heaart and thus makes it stronger...
That's mainly everything you need to know, I think...
...?Considering TornZero did that with a Zorua (Burst Heart), I don't see a problem with that, just as long as you don't use it every five seconds it's alright.