Poulin, 21, leads all Sound Tigers goalies with six wins this season. The Montreal, Que., native has a 3.37 goals-against average and an .892 save percentage in 13 appearances.
Poulin appeared in 10 games last season with the Islanders, posting a 4-2-0 record with a 2.44 GAA and a .924 save percentage.
The Islanders selected Poulin in the fifth round (126th overall) of the 2008 NHL Entry Draft.
Wallace, 27, leads all Sound Tigers with 20 points (nine goals, 11 assists) in 24 games this season. A native of Anchorage, Alaska, Wallace has played 24 career NHL games with the Pittsburgh Penguins, totaling two assists and 12 penalty minutes.
The Islanders signed Wallace as a free agent in July, 2011.