No he doesn't...
Hoenn:
Water Gen 3 - Morrison had Swampert
Grass Gen 3 - Tyson had Sceptile
Fire Gen 1 - Harry Potter had Charizard, Harrison had Blaziken but he went to Johto...
Ash had Grovyle, a middle stage.
Also, in Johto:
Water Gen1 - Gary had Blastoise
Grass Gen 2 - Vincent had Meganium
Fire Gen 3 - Harrison had Blaziken
Ash had Bayleef, a middle stage (And Charizard, but he's not from Johto, well, he moved to Charicific Valley, but that don't count).
In Unova:
- Trip has Serperior
- Bianca has Emboar
- Burgundy has Samurott?
Ash has Pignite. A middle stage...
Seeing that means that there is a very large chance that nothing further happens to the starters at all until the league. Sinnoh was an exception to a trend that was established in Johto.
Guys, here were the fully evolved starters used by league rivals in Johto and Hoenn.
In the Johto League:
[img139]http://sprites.pokecheck.org/i/009.gif[/img139][img139]http://sprites.pokecheck.org/i/154f.gif[/img139][img139]http://sprites.pokecheck.org/i/257.gif[/img139]
Gary's Blastoise, Vincent's Meganium and Harrison's Blaziken.
In the Hoenn League:
[img139]http://sprites.pokecheck.org/i/260.gif[/img139][img139]http://sprites.pokecheck.org/i/254.gif[/img139][img139]http://sprites.pokecheck.org/i/006.gif[/img139]
Morrison's Swampert, Tyson's Sceptile and Ash's Charizard.
In the Unova League I might expect:
[img139]http://sprites.pokecheck.org/i/497.gif[/img139][img139]http://sprites.pokecheck.org/i/500.gif[/img139][img139]http://sprites.pokecheck.org/i/503.gif[/img139]
Trip's Serperior, Bianca's Emboar and Burgundy's Samurott.
If Ash's Oshawott doesn't evolve (becomes Piplup 2.0), Burgundy will showcase Samurott. If Oshawott does evolve but Burgundy doesn't evolve Dewott, then Ash might have Samurott.
I am most likely seeing Pignite as Ash's powerhouse starter this saga cos starters that evolve often become powerhouses, if Oshawott stays unevolved due to marketing then he isn't the powerhouse.