There is no one best pokemon in the game. There are multiple pokemon with similar stat ranges, such as Groudon, Kyogre, Rayquaza, Jirachi, Deoxys, etc. However, how well they perform is up to the trainer.
deoxys if you can get it
rayquaza
Ditto.
rayquaza
Pokemon snap or Pokemon emerald
you evolve a duskull at lvl 37 one of the best ghost Pokemon on emerald
torchic
yes he is probably the best pokemon in pokemon emerald
the best Pokemon region is hoenn { ruby,Sapphire,emerald }
in emerald its torchick
rayquaza and mew!
chincypops
The best Pokemon in Emerald version is obviously Rayquaza!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!DUHH!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! A: YEEEEEEEEEEEEEEESSSSSSSSSSSSSSSSSSSSS!!!!!!! I luv Rayquaza! But technically I suppose Jirachi would be but that's an event Pokemon.
The best emulator is NO$GBA