For my 1st run, definitely my Accelgor and Sceptile. Accelgor's stupidly high S.Atk and awesome speed easily win me games, 1 Bug Buzz is enough to #RECK Terra's Giovanni the Nidoking. While Sceptile have lots of "Blade" skill, like Night Slash, Leaf Blade, X-Scissor, etc which provide a lot of thing you could do, alongside high S.Atk to set up Leaf Storm
In my current Dark-monorun, its pretty much Greninja and Honchkrow.
Greninja being Uber pretty much said what is so good on him, while Honchkrow destroy any fighting type I'm against with Brave Bird/Swagger+Foul Play combo