Indigo league:
http://www.serebii.net/anime/pictures/indigo/082ps8.shtml
Bottom two pictures include a threesome of trainers atop a pedestal.
I actually thought about this minileague scenario this afternoon.. and yeah, I don't think they will, but it could just be the last showcase for some you know. Nobody wants a minifinal, but it's the last credit you can get after losing in the knock out stage. With this in mind, they'd only have to show some of the battle, as in: the only few pokemon that weren't used that were in the opening, which are: Bayleef/Totodile/Muk/Glalie/Corphish/Torkoal.
Assuming the Johto team gets Makuto, that means the latter four of that list could be in that thirdplace final. Maybe Pikachu would be knocked out from the Darkrai battle as this would be the last battle of Sinnoh, and Donphan could take it's place, but you never know.. xD
This is probably just going to end as the hope for a
second dark horse trainer. But anything worth speculating about is worth a post or two, so here's my second post on the matter xD