you will need a good level pokemon but your types can be either water,fire or ground. and fight The best pokemon against steel type is fire type pokemon......train your fire type pokemon to high level before you fight with the gym ....
Reshiram is a Dragon- and Fire-Type Pokemon, which no other Pokemon has the same combination. Reshiram is the only Fire-Type that isn't weak to Water-Type Pokemon. Reshiram has the highest Special Attack of ALL Fire-Type Pokemon.
A Fire-type Pokemon can deal 2x the damage to Grass, Ice, Bug, and Steel-type Pokemon.
Darumaka is a Fire type pokemon.
Pansear is a Fire type pokemon.
water or fire type on a high level (above his)
A fighting type, Ghost type, Fire type, Rock type, Dragon type, Ice type, Water type.
You can beat it with Ground type Pokemon or Fire type Pokemon easily.
Gyarados is always a water/flying type, you can teach it fire type moves though.
Torchic (fire-type), Mudkip (water-type) and Treecko (grass-type)
get a fire type
Fire, fighting, steel and rock
The rarest you can get is groudon who is a fire-machine type pokemon.
In Pokémon Ruby (and Sapphire/Emerald) the three starters are Treeko (Grass type), Torchic (Fire type) and Mudkip (Water type).
Type Pokemon Ruby and then type CCG.
Primal Groudon is a fire and Ground-type Pokémon and will be seen in the Omega Ruby and Alpha Sapphire game.
In the 3rd generation of Pokemon (Sapphire, Ruby, Emerald, Leaf Green, and Fire Red) it is easily agreed upon Pokemon users that a fire type of Pokemon is the best for advancing through the game easily. However, it is best to have a wide range of Pokemon types in your party because every Pokemon type has type advantages and disadvantages. So if your person your battling has a Pokemon that has a type advantage over you, (example: he has a water Pokemon and you have a fire Pokemon) switch out to a better one. This is very important for the elite four since each person has a different type of Pokemon.