You can't catch one anywhere in Emerald. You'll have to trade one from FireRed/LeafGreen.
no you cant catch diglett on Pokemon ruby because diglett is too old he comes only back in Pokemon diamond
u cant
First you got to catch him in Pokemon leafgreen or fire red and trade. Or you can use a gameshark. it lets you catch all the Pokemon from bulbasaur to deoxys.
around survival area
Dialga Palkia, Rayquaza,Kygore and Groudon
Diglett or Dugtrio
You'll have to trade from Pokemon FireRed or LeafGreen.
If you are trying to catch Cresselia I would swap Diglett for one of our stronger Pokemon (click x then go onto the Pokemon section, click the Diglett and press switchto switch it for one of your stronger Pokemon before the battle). Diglett cannot learn Mean Look, or any of the other blocking moves such as block and Spider Web.If I were you I would use different Pokemon to catch Cresselia.
In Pokemon emerald and other Pokemon games bad eggs are glitch Pokemon called missingNo. that will mess up your game if you catch them.
You cannot catch Diglett in Pokémon Emerald, you can only get it through trading.no where you need to catch it in L.G OR F.Ryou can't but you can get him from leaf green or fire red
He never caught one
Buy the TM Dig or catch any Pokemon that already knows it. A common one is Diglett.