Just for the heck of it, here's another more offbeat Defenders team.
A master of the occult -- Magique, with Satana to spell her from time to time. (Sorry, pun.) Magique comes to Earth seeking the aid of the Sorcerer Supreme.
An expression of pure, brute force -- Maxam. He needs to be revamped starting with his costume, but any character that can go toe to toe with Hercules or Drax checks this box.
A water elemental -- Iceman. Bobby is awesome.
A strong presence to lead them -- Moon Knight. If Batman can have his Outsiders, MK can have his Defenders.
The rest of the team:
Silver Surfer: At least one original member of the Defenders (up to and including Red Guardian) would appear on any Defenders book that I pen. Norrin is my favorite, so he gets the first tour.
Hepzibah: Another favorite of mine. I would have her and MK bump heads initially, because Hepzibah's trust has to be earned. Her fighting prowess and technical skills are invaluable to any team.
Copycat: I believe the original is dead, but I'm happy to establish that she was not the only Copycat. In fact, I'd probably suggest something crazy like Copycat is one of the few mutants whose powers were triggered at conception. She replicated in her mother's womb, resulting in a virtual litter of 13 infants. Unfortunately, only seven of the infants survived delivery and subsequent medical treatment. This Copycat sibling would love nature, animals and critters of every kind to the point that her mimicking abilities are limited to flora and fauna. Think of Vixen, only Copycat can also replicate properties from plants...like the ability to heal or poison you. Her kiss would have the power to cure or kill you...so be careful not to get on her bad side.