The 29-year-old scored his sixth Premier League hat-trick in a 6-0 romp over Watford at Vicarage Road.
Aguero is now just three strikes away from becoming City's all-time leading scorer - a title that has been held by Eric Brook since 1939 when he reached 177 goals.
"He's very special, just a goal machine," Gundogan told the club's official website. "His last goal was incredible, it showed all his talent and how powerful he is. We need him and hopefully he'll score a lot more goals."
The Argentine's goals have helped City claim an unbeaten five-game run, which takes them to the top of the league table.