Yes, You can catch Groudon in Pokemon Emerald.
You can't catch one in Pokemon Emerald.
No you cannot catch Entei in Pokemon Emerald.
You can't catch a Bellsprot in Pokemon Emerald. You trade it from Pokemon Leafgreen!
You can find it by using a Super Rod on Iron Island.
You can only get Qwilfish in Emerald by trading from Firered.
Qwilfish is rarely found in Routes 12, 13, and 32
Qwilfish can't be caught in emerald trade one from firered or Pokemon colosseum to get one.
Yes, You can catch Groudon in Pokemon Emerald.
You can't catch one in Pokemon Emerald.
No you cannot catch Entei in Pokemon Emerald.
You can't catch a Bellsprot in Pokemon Emerald. You trade it from Pokemon Leafgreen!
Fish for it outside of iron island with a super rod ;)
You can find it by using a Super Rod on Iron Island.
There are many Pokemon you catch that are similar in sapphire and emerald but there are many Pokemon emerald can only get and not sapphire.
Cressilia is a 4th generation Pokemon so you can't catch it in Pokemon Emerald.
You can't catch or obtain other trainers Pokemon in emerald.