I have to admit here and now, I didn't see this coming at all. I had reasoned as followed.
1) Many, many people would love to beat the ever-living crap out of Ash or a look-alike.
2) Ash or a look-alike are both completely devoid of viable combat skills.
3) Therefore, Ash and/or a look-alike are not viable as fighters, although they'd make excellent shoe-in replacements for the home run bag.
Obviously, Nintendo thought differently.
Sadly, we will not be able to beat the ever-living crap out of the trainer himself, but only his pokemon. This is fine, so long as they don't use Ash's whiny voice. I will change the voice options to Japanese without blinking if I hear that horror upon horrors again.
In any case, it looks like we're going to see a lot of very unique fighters. Ridley's chances just shot up, in my opinion.