At present what we have are different weapons generations that essentially all stick to the pistol-rifle-sniper-shotgun-machinegun pattern. It would be nice if each generation had at least one difference to this pattern so you had to change up tactics and couldn't just stick to the same model through the whole game, and also introduce interesting alternative weapons.
My suggestions would be:
Accelerated: should introduce a single-shot RPG-style launcher.
Laser: a "laser shotgun" makes no conceptual sense and seems to be there just because generations of weapons follow the same pattern, replace it with a heavy laser (i.e., something firing wide, powerful laser blasts that clear terrain) similar to the heavy laser in the original X-Com.
Gauss: change up the pistol and replace it with a Gauss mini-Uzi firing (inaccurate) three-round bursts.
Fusion: not sure but the key-word here should be "explodey".