There is a lot to list on here so I will link you to a Bulbapedia article
about all the missingno glitches and a short explenation about them.
Depositing a Glitch Pokémon in the PC, looking at its stats, and withdrawing it will turn it into a Rhydon.
This rumor is half true. There is a short explenation of it in the link I posted.
If a Missingno. is caught and sent to Bill's PC, the game will freeze if you try to withdraw it.
This, however, is just false, so you don't need to worry about it.
Hope I helped!