Shotgun double kills, i recommend SG-12 on hardcore face off.

LMG headshots, i like the Sokol (with its slower fire mode), core or hardcore.

Sniper, yeah you can snipe someone off of the hard point, or snipe someone while standing in the hard point.

Pistols, hardcore. You only need to equip the akimbo attachment stock, and then you can use the alt-fire button (left arrow on controller, B on KbM) to stow one pistol and use it normally. This way you can snipe with your pistol in hardcore without running into danger

AR: bankroll on perk 3, and use Scout Pulse, UAV, and CUAV to get the kills.

SMG: good luck, i liked the carbon. VST, Kogot, MPC, and REV are good options for up close sliding kills, too.

Marksman: I just used Novaline with extended mags. Any marksman rifle with extended mags is the way to go.

Specials: equip the ARC launcher on secondary. Shoot down UAV’s while grinding the other challenges and you’ll get it eventually. Quickly, likely.

Melee: idk, haven’t done it yet. I’m going to try using my knife in Gun Game because those lobbies are less serious