I just founded a shiny Camerupt in Pokemon Platinum with full odds!!! My first shiny was a shiny numel in pokemon sapphire in like 2009. Around three years I lost that game while traveling - it had my first level 100 and a total of 550 hours before the clock stopped. I recently started to shiny hunt using the pokeradar in Platinum, but when I found the shiny it was not part of any chain (chaining increases odds). Camerupt only has a 20% of being encountered in the area I was in. Thank God that was not a golbat or ferrow.
Since Camerupt is shiny, 1/8192 and then multiplied by the odds of encountering a Camerupt at all 1/5 gives me 1/40,960. (Hopefully my math is not too horribly off)
Edit: I cannot describe how insanely happy and excited I am. Literally this made my year. This is the highlight of my luck. like in 2016 I opened 10 packs of holon phantoms and got a gold star pikachu. RNGjesus has done me well. On cloud 9… no, cloud 40,960