I have trouble thinking Elizabeth would willingly fight her father. Considering that in Omega Flight she looked to practically take over the mantle of Shaman. However working with the gov't as Alpha's spy I'll accept.

Puck leading a team would be interesting and he'd be damn dangerous too. I'll leave the why to Fred and Greg. Others I'd add are:
Puck II (Zuzha): Lots of good moments to be had here, she'd finally meet her real dad and fight beside him, but does Eugene want that?
Nemesis: Just because she's so bad ass with a cool costume.
The Plodex Kid (vol 3): Rapidly aged and trained. Marrina would be his target.
Box: Poor Jeffries, so easily manipulated, this time by his own gov't. Creates Box power suits manned by the military.
Madame Web (Julia Carpenter): She is reactivated by the Canadian gov't and brought aboard. Now with her seer-like powers she poses the biggest threat to Alpha Flight.
Omega: Pointer is promised control over the voices in his head and an endless supply of "juice" if he cooperates.
Wendigo: A new person has obtained the curse but with Talisman's help is able to stave off the feral madness.

Alternative: Having no super-powered individuals the Canadian gov't trusts to bring Alpha in they turn to their allies across the sea and ask for:
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