Using the lavaridge egg codes, you can get missingno. here are some codes :-----------------------
MissingNo. Egg
Ruby: 320B31B9 8795B1B9
Sapp: 16903EAB 2789E501
AR v3
-----------------------
MissingNo. Egg
Ruby:
FD78F257 F6D1C816
F8A224A7 5C90B52B
Sapp:
9B78FA02 2FF826E7
F8A224A7 5C90B52B
Here are the rest of the codes you will need :
GS/AR v1/v2
-----------------------
(m)
Ruby:
9E6AC862 823AB7A8
46B7D9E4 A709E9E1
Sapp:
9E6AC862 823AB7A8
8365F8FA 817CF3E9
Lavaridge Egg Enabler
C6500699 A423FC68
Fast Egg Hatch
D7A2E463 9F64ABFA
AR v3
-----------------------
(m)
Ruby:
DE00AAFD 2EBD05D0
530823D9 16558191
Sapp:
DE00AAFD 2EBD05D0
B4564EFE 23F44BF2
Lavaridge Egg Enabler
46813A10 82A13FB1
Fast Egg Hatch
9E17B966 367DE205
I got this codes from soapman's glitch guide on gamefaqs.com. This is the code for the safe missingno that doesn't mess up your game. It says "Get the egg from
the lady, hatch it, viola, a new little bundle of joy."
Although it has been a long time, I can verify these codes work, at least on sapphire. I just started a new game on a ruby rom and when I get as far as lavaridge I'll let you know if they work there too.
Anyway, This pokemon only has one attack, and it is a normal pokemon. There are alot of codes on loadingNOW's and Mastersord's code guides on gamefaqs. I'm not sure which the code is on, but one of them has one to make any pokemon learn any tm/hm move, which should work for missingno (i hope). I haven't tried that yet. Also, there are scails you can get that can teach any moves to pokemon. There are also codes for that.
Here are the links:
https://db.gamefaqs.com/portable/gbadvance/file/pokemon_rs_na_gs.txt ---loadingNOW's code lists
https://db.gamefaqs.com/portable/gbadvance/file/pokemon_rs_gs.txt -- --mastersord's code lists
and for the heck of it,
https://db.gamefaqs.com/portable/gbadvance/file/pokemon_rs_glitches.txt ---Soapman's glitch guide
These are long lists so to find the ones you need I suggest you use ctrl + f and then type in what you are looking for, or you the handy number system and type that in find.
I hope this helps.
(EDIT)
Ok I got a Missingno, I don't think the fast hatch I gave you works, but this one does : 9E17B966 367DE205
Also if that missingno code doesn't work, this one should: CBD2E675 36131AFD . I think these codes work for both games.
I have attached a image of Missingno's nickname screen. His original name is ????.