In Kirby Squeak Squad, Kirby's motivation for starting his adventure was that his cake was missing. In Super Smash Bros. Brawl, he was revived because, in his hunger, he ate one of Dedede's magic pins.
Kirby often gets into situations due to his carelessness (and being a Big Eater), but once he's aware of a problem, he's too active in fighting whatever miscreant is involved to be a Fool.
The Jester class in Dragon Quest 3 (known as the Goof-Off in the NES version) and almost every Dragon Quest game thereafter. They are almost always either uncontrollable or very weak or both in battle, and every stat is a Dump Stat except for Luck, which is where all those points went. Their high luck, however, enables them to have much stronger a chance of inflicting a critical hit when they do successfully attack, and to have a greater chance of a win in the gambling minigames if you can't or don't want to do Save Scumming. Also, in most of the games, after a certain point, they are the only class that can become a Sage (healing AND attack magic) without a special item.
An inversion of this trope, in Persona 4, the protagonist's friends social link as the Investigation Team under the tarot of The Fool. Despite this, they grow and learn from the end of the game, and eventually re-social link under The Judgement.
Same in Persona 3 and you even start out with a Persona of The Fool Arcana. There's a bit of a visual shout out even, with the female character in the PSP remake, where her hairpins are arranged as XXII.
Both games invoke the true extent of the Arcana so hard that it becomes a serious case of Shown Their Work. The protagonists of both games "main" (starting) arcana is The Fool which grows to the Judgment and, for the protagonists themselves, The World/Universe. Additionally, they're both Heroic Mimes. This might seem like standard RPG procedure until you realize that they're mimes because they have no pre-defined personalities to speak of, allowing them to fit their personality into any mold they see fit (which is why they can have such profound effects on so many people).
She's really only unlucky with things concerning her sucky destiny. There are sometimes she has avoided attacks sent at her by tripping. Due to similar things happening, Zelos suggests they should let Colette trip on the way to buy a lottery ticket.
In SuperStreet Fighter IV, Ryu is this according to fortune teller Rose, which means he is the only one who can defeat M. Bison for good.
A lot of comic Adventure Game protagonists could fit the bill but Bwana from The Journey Down is exceptional even among them. For proof, he'll fly a seaplane with his eyes closed, install ship (as in, from a yacht) engines on said plane by flinging them with a crane, and attempt to cook with engine oil. And he'll survive and be impressively successful every time.
Reimu Hakurei is an interesting case in that she isn't entirely clueless. However, her mind works very differently from most people's (even considering that "common sense" is a rare thing in the Fantasy Kitchen Sink the games take place in to begin with) and her extreme luck is what allows her to respond to most every incident that occurs with the same course of action: pick a direction at random and go, because no matter what, her luck will lead her to the Big Bad so she can stop them. Amusingly, her best friend is a magician, just like in Tarot.