Here is my suggested Garchomp for you
Garchomp @ Leftovers/ Smooth Rock
EVs: 252 Speed/252 Atk/ 4 SpDef
- Hones Claws
- Fire Fang
- Dual Chop
Hones Claws are too boost the low accuracy of your moves and boost the attack. Fire Fang is to take care of that ice weakness. I choose Dual Chop because it hits the opponents hard(after a Hones Claws boost) and it's a Sub breaker.
Also look here for move sets. Look here on where to raise for EVs.