Pettersson, 25, was an AHL All-Star in 2018 and had team-best totals of 22 assists and 33 points in 49 games for the Milwaukee Admirals this season.
A sixth-round draft pick by Nashville in 2013, Pettersson skated in 72 games with Milwaukee last season and led the Admirals with 33 assists and 46 points.
Pettersson, the older brother of Vancouver Canucks rookie Elias Pettersson, began his pro career in his native Sweden playing for MODO Hockey, Skelleftea AIK and Vaxjo Lakers in the SHL.
Dauphin, 23, has six goals nad 14 assists for 20 points in 34 games with the AHL’s Tucson Roadrunners this season. He also appeared in one NHL game for the Coyotes.
A fourth-year pro, Dauphin has totaled 44 goals and 58 assists for 102 points in 192 career AHL games with Tucson, Rockford, Springfield and Portland. He has added three goals and one assist in 35 NHL games, all with Arizona.
Dauphin was originally a second-round choice by the Coyotes in the 2013 NHL Draft.
Helewka, 23, had a team-leading 13 goals for Tucson this season and ranked second on the club with 31 points in 41 games.
In his third pro season, Helewka has registered 36 goals and 63 assists for 99 points in 165 career AHL contests with Tucson and San Jose.
Helewka was originally selected by San Jose in the fourth round of the 2015 NHL Draft.