I've found 5 shinies in the >900 hours I've poured into every pokemon game I've owned...
The first was a Shinx (Platinum, first playthrough)
Second was Tangela (Soul Silver)
Third was Lunatone (White version about a month ago)
And the last two were Foongus and Amoongus found within a 10 minute window of each other not four days ago....
(This is not counting shiny events, since they are GIVEN to you...)
How would I do? Well, I don't have a bad team per-say...
I mean, I'd certainly be looking to trade the mushrooms... But with Electric, Grass and Psychic they're not (strictly speaking) BAD types, since they both compliment each other...
EDIT: And all things considered, since the odds of finding a shiny is roughly 32000/1
Although breeding via Masuada method (Using international parents) doubles the odds... But I wouldn't hold my breath...
EDIT 2: That being said, I learned to RNG my Pokemon White game, so, I should probably start catching more.... ha ha ha