Serperior
-leaf blade
-dragon tail
-toxic
-coil

Swanna
-aqua ring
-brave bird
-surf
-aerial ace

Gigalith
-earthquake
-stone edge
-curse
-heavy slam

Haxorus
-dragon dance
-dragon claw
-earthquake
-rock slide

Chandelure
-calm mind
-flamethrower
-energy ball
-shadow ball

??????????? (maybe boufallant, stoutalnd, mienshao, galvantula, conledurr)

Since you have Swanna on your team, and you're considering Stoutland, I'm guessing this is an in-game team, in which case anything will work. As my sig will show, I'd personally go with Stoutland or Bouffalant.

Your team is slightly lacking defensively, personally id go with conkeldurr. It is quite bulky and with drain punch can be really tough to take down
Heres a good moveset-
Conkeldurr @leftovers
-mach punch
-drain punch
-stone edge
-bulk up/earthquake
Hope this helped