Magnemite is #81 in the national pokedex, and it is an Electric-Steel type Pokemon.
In Pokemon Diamond and Pearl you need the National Pokedex to get Magnemite. In Pokemon Platinum you don't need the National Pokedex to get Magnemite.
Magnemite=Fuego Ironworks Beldum=Route 228(mass outbreak) Magby=Route 227,Stark Mountain(After obtaining the national pokedex) Elekid=Route 205,Valley Windworks(After obtaining the national pokedex) Yanma=Pastoria Great Marsh(After obtaining the national pokedex) Nosepass=Route206(MAss Outbreak)
In the National Pokedex Muchlax is number 446.446
Growlithe is number 58 on the national pokedex.
It cannot be found until you have obtain the National Pokedex. Magnemite only appear in 'Swarms', where a certain place is swarming with that particular pokemon and cannot be previously obtained.
You can make Magnemite appear in Fuego Ironworks as a Swarm after you obtain the National Pokedex from seeing every Pokemon in the Sinnoh Pokedex. To know if Magnemite has appeared talk to your rival's sister in Sandgem Town. If Magnemite hasn't appeared try again the next day as Pokemon Swarms change every day.
Gyarados is #130 in the National Pokedex.
Croconaw is number 159 in the National Pokedex.
Eevee's number in the national Pokedex is #133. If you don't know what the Pokemon's number is then go to pokemondb.net/pokedex/national It is a great site to find Pokemon's number!!
Sceptile is number 3 in the Hoenn Pokedex and number 254 in the National Pokedex.
Shaymin is number 492 in the National Pokedex.
It's number 197 in the National Pokedex.