Hi i'm new here! I was trying the old man glitch for the first time and some weird stuff happened! So I did the old man glitch and initiated a battle with missingno on cinnabar island and when I got in the battle I used a master ball on missingno and it said I caught it! Then it prompted me with the "Would you like to change the name of your pokemon?" And I pressed no. Then a strange loading screen popped up for a few seconds then it randomly put me in a battle with a missingno with a stranger name. So I decided I would catch that one to! When I caught it, it said I caught a ditto? And then when I went to check my pokemon I had my main pokemon, a ditto and pokemon with a strange name and then the picture where the pokemon would usually be was a picture of my rival!? And when I checked the stats its type was bird and normal??? It had the attacks water gun, water gun and sky attack. and had 777136 exp points. I don't know, I thought this was crazy and had to post it some where. Sorry if I posted this is the wrong category.

This is common.

M' or Missingno. occasionally becomes a ditto in battle after catching.
But hey, you get a free ditto more or less!

Yeah this is a pretty...common thing when performing the Missing No. glitch? Although, the other Missing No. I think you're referring to is 'M. It's not the same as Missing no. but similiar. Missing No (and 'M) are always Bird/Normal type, also, if I recall correctly.