Ok, first off, let's get this settled:
Good Oli players have a huge advantage over jiggs because of all the reasons mentioned above, and Olimar will never be in a gimpable position. He will stay in the middle of the stage.
Inexperienced Olimar players will not always be in the center of the stage and be gimped by jiggs like mad.
It’s Olimar's biggest weakness as a character. Why would any decent Olimar player not avoid this?
Since we are talking about good Olimars, I would say the matchup would be 70:30 or 65:35, but not higher.
There are almost no way jiggs can approtch Oli, etc etc. All this way mentioned on 9 pages.
The trick is to get Olimar in the air and attack him there. It doesn't matter if Olimar has an excellent or just decent air game; it sucks compared to his ground game. Therefore, Jiggs will be able to attack him much easier. Here, you can try and gimp him (Jiggs' bread and butter in this matchup), but it will be extremely hard to do. If an Olimar didn't know how to not get gimped, he would suck. Even if he has a high percentage, this is the preferable method for getting the KO, since its hard to land another KO move. Getting him offstage is the trick for this matchup, since it will at worst rack up some damage, and at best result in a loss of stock. It won't be easy to do this, however.
But that said, Jiggs doesn't have to do poorly with olimar, you just have to learn ways around the matchup. Japes is a great stage for this matchup, but I've had an Olimar camp under the platform in the center and be untouchable. It was quite annoying.
Also, Zori, do you remember the ranked match we had on AiB? They were intense matches, and pretty even, too. My Jiggs even did well on Luigi`s Mansion. You won in the end, but it was still close.