You mean Master Balls, right? It multiplied the 6th or 9th(i forget which) slot item by a lot. In blue version, it was lv. 151, with these moves:
1.Water Gun
2.Water Gun
3.Sky Attack
I know. It has two Water Guns.
It had two types, Type1=BIRD TYPE2=NORMAL.
Note that it's BIRD, not FLYING.
If you catch it, your Hall of Fame becomes horribly glitched, with tons of weird looking glitchy squares, changing music, and Mew will probably appear there a few times.
If you gave it a Rare Candy, it would evolve into a lv.100 Kangaskhan, with the same moveset.
You could find Missingno. by surfing up and down on the east coast of Cinnibar Island, where the land and water meet. Besides finding Missingno., you would find other strange pokemon, probably over level 100. A level 257 Pidgey for example.
If you try to trade it into Gold/Silver/Crystal with the Time Capsule, it will appear on the newer generation as a Remoraid. If you select ti for trade, the game will tell you:
"This is an irregular pokemon and can not be traded!"
Or something along those lines.
Or, instead of reading al lof this, why don't you just look up Missingno. on Wikipedia.