Yes, but only if you chose Mudkip as your starter and then your rival will use Treeko as their starter Pokemon.
for emerald, raquaza, groudon, kyogre, your starter pokemon, magnemite and wailord.
Swampert or Wailord.
I used my starter pokemon(whitch was blaziken) My regi rock registeel and regi ice( from saphire) a tyranitar, and a castform.
The only two ways to get a torchic in emerald is to choose it as your starter, ortrade with another emerald, ruby, sapphire user that has it.
You can only get one of the three Starters in Pokémon Emerald without use of cheating or trading. You can trade or use an action replay code to get all three (I don't know the code, so I can't help you there). Hope this helped.
Sceptile's leaf blade
NO you can not play Pokemon emerald in Coloseum.
you use pal park to get emerald Pokemon to pearl bur you can't transfer them back to emerald
simple use action replay or migrate from leaf green or fire red not ruby or sapphire or emerald ;)
Personally, I always use fire pokemon starters. I think they are the best. If i were you, I would get the Chimchar.
Gardevior psychic on tentacruel thunderbolt on the rest except whiscash use Breloom