yes tou can
yes
i don't have Pokemon emerald, but the answer is always the same. not how long. how many steps. walk ALOT and the egg will slowly start to hatch
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Breed a Wigglytuff hatch the egg to receive igglybuff.
Put a starter with a ditto in the Pokemon daycare and wait for an egg hatch it to get the baby starter.
No hatch it first then release the Pokemon inside if you don't want it.
keep it in your party, make a fire Pokemon as the leader so it will take less time to hatch
run/ride around quickly. Once you've taken a particular amount of steps, the egg will hatch
if you got an egg and you want to hatch it fast then get a mach bike and do sandy slopes that will reduce half of the steps and also keep a fire Pokemon with it and also do a lot of bike riding
your egg hatches when it is around energetic Pokemon the higher you Pokemon are in level and health the faster tht egg will hatch but you have to walk around and battle as well i recomend riding your bike ......A LOT
Walking
3000-5000 steps about im not 100% percent sure