Give it Magnet Pull or Arena Trap, or at least regular Stunfisk's abilities if we are looking to just use super situational abilities
Make Mimicry work like Forest's Curse/Trick or Treat instead of Camouflage, keeping as many of its resistances it can in terrain
Bring back Secret Power and give it to Stunfisk for terrain shenanigans

Did I fix it? Does it need STAB Steel moves or have Snap Trap changed to Steel as well?