The phrase "new controller" refers to someone or something that has recently taken charge or control of a situation or a group of people. Full definition
They also announced that they will be releasing brand new controllers for the game and upcoming peripheral. (condemnorcondone.com)
I have a feeling that 2018 will bring us an assortment of new controller colors, so I'm just waiting to see if my hypothesis is correct. (nintendoenthusiast.com)
They also said the system will be playable on the show flow which means they would be showing off the new system's new controller as well. (nintendoworldreport.com)