firey path or the just outside the cave. Marill should pwn numel do to its double weakness.
Marill is a good Pokémon if you're facing something that is weak against water. In competitive play it is considered fairly weak.
Pokemon you can get with the good rod are: TENTACOOL, MARILL, MAGIKARP, CHINCHOU ( under-water ) and CORPHISH.
If you want a good place to level up your pokemon, I highly recommend the Iron Island or the Fuego Ironworks.
In Pokemon Diamond, a very good place to go is North of the Fight Area. All of the many trainers have level 45-60 Pokemon.
If use the good rod around pacifidlog town you may find it.
In a pokewalker.
I have soul silver but i guess the Pokemon league.
in elite 4.
Well that is a hard question. It all depends on the level of your pokemon. To train level 25-30 pokemon the best place is Desert Resort. Another place that is good is Cold Storage.
mt.silver is a good place because it has lvl.50 pokemon there
Nowhere.
Anywhere that u find Pokemon that are close to the shromishes level.