I usually play Human Vanguard in multiplayer, and Bronze difficulty is a breeze. Silver I can win with some difficulty, but Gold seems especially difficult as a melee-spec character.
I'm specced out for pure Melee damage and I usually carry a shotgun with + Melee damage so I can kill "weak" targets like Cannibals/Cerberus Troopers in one punch, but the top tier enemies like Banshees/Atlases are hard to survive, especially when there's more than one. Cerberus turrets are also a huge problem.
What I'm currently not doing much of is bringing weapons along (usually just a shotgun to keep weight low) or using Shockwave; the limited range doesn't seem to help much.
Is it possible to beat Gold reliably with a Melee spec character? Human Vanguards or Krogans in general are to my liking.
Should I just stay away from the big baddies like Atlases? On Bronze I take them out with a charge/Melee/Charge combo, but on Gold it gets me killed, and my Shotgun is mostly useful for Melee damage and hitting downed targets, it doesn't hurt the big targets worth a darn.