For a fire type I recomend camerupt I guess.
Camerupt
ability: solid rock
evs: 252 def; 252 sp def; 4 hp
-earth power
-fire blast
-stone edge
-flash cannon
I wouldn't recomend keeping both metagross and slowbro but movesets:
Slowbro
ability: own tempo (for elite four who love confusion)
evs:252sp atk; 132 sp def; 124 def
-surf (power and transport)
-psychic
-shadow ball
-ice beam
Metagross
ability: clear body
evs: 252 atk; 132 sp def; 124 def
-meteor mash
-zen headbutt
-hammer arm
-earthquake
If you get rid of slowbro:
tentacruel
ability: clear body
evs: 252 sp atk; 132 def; 124 sp def
-surf
-ice beam
-sludge bomb
-dazzling gleam
if you get rid of metagross:
Bisharp
ability: inner focus
evs: 252 atk; 132 sp def; 124 def
-iron head
-night slash
-brick break
-x-scissor
sceptile
ability: overgrow
evs:252 speed; 252 sp atk; 4 hp
-energy ball
-dragon pulse
-focus blast
-nature power
altaria
ability: natural cure
evs: 124 sp def; 132 def; 252 hp
-moonblast
-dragon pulse
-fly
-fire blast
stoutland
ability: intimidate
evs: 252 atk; 252 speed; 4 hp
-play rough
-return, facade, or retaliate ( my choice)
-wild charge
-crunch
Hope I Helped!!!