There wasn't anything special about him. He wasn't supposed to be a villain that was more powerful than anything else like in DBZ. His character was particularly crafted and designed to be more of a symbol in the context of Boruto's personal story arc.
We were introduced to Boruto as a character that was looking for any shortcut he could; a character who preferred loopholes and instant gratification as opposed to actually working toward a goal and achieving it.
Momoshiki and the other one were introduced to us as villains that their whole gimmick was they stole power from an outside source and returned it several times over. They had nearly no special abilities of their own outside of that. They were just powerful enough to cause some problems for an out of touch Naruto and just powerful enough to have a pretty fair fight against a one armed Sasuke individually, but not so powerful that Naruto and Sasuke were forced to become the main characters and overshadow Boruto.
In context, they were meant to be shown as inspiration for Boruto. They came, they temporarily took Naruto out of the equation, and they left. Boruto had to make up his mind and develop as a character to rescue his father with his own power. Then after Boruto had completed his own personal arc, Naruto and Sasuke came together and struck the final nail in the coffin when they demonstrated to Boruto that hardwork and using your own personal power is greater than cheap tricks.