A common counter argument to Dawn's heavy presence in Journeys is that it was just cross promotion for Pokémon Brilliant Diamond, Shining Pearl, and Legends Arceus. While those games definitely gave the executives a reason to bring her back, promotional timing alone does not fully explain why she stayed so central during the Masters Eight finale against Leon.

Think back to the Sinnoh era. DP was widely regarded as the narrative peak of Ash's original growth. His rivalry with Paul pushed him to his absolute limits, his team was deeply tactical, and the Tobias loss always felt like a sudden block thrown in because the decision was made to keep the anime going into Unova. If DP was originally envisioned as the ultimate end to Ash's original run, Dawn was designed to be his final co protagonist. She was given equal billing, her own complete arc, and that iconic high five motif representing two sides of the same journey.

When BDSP came out around the time of Journeys, it was convenient corporate alignment. But look at how the writers handled her during the climax against Leon compared to other past companions like Serena, May, Brock, or Cilan. Those companions were shown briefly watching from TV screens in their respective regions. Dawn, however, was in the actual stadium, getting constant reaction shots and emotional focus during the most critical battle of Ash's life.

By the time Ash was battling Leon, the main BDSP promotion window had already passed. If her presence was strictly a corporate commercial, she would have left after the Darkrai and Arceus special episodes.

Instead, the writers kept her around because she represented the climax of Ash's golden age. Having her stand out so prominently during his world championship victory was a thematic nod to the era where Ash was closest to reaching his peak, effectively bringing his character arc full circle to the companion who shared that era with him.

And before anyone brings VA issues, Brock's Japanese Voice Actor Yuji Ueda plays both Wobbuffet and Brock. Wobbuffet was there and he even had a speaking role. Dawn being at Ash vs Leon was a narrative choice not a promotional nod

If DP was originally intended to be Ash's final series, Dawn watching Ash vs Leon among all other past companions makes total sense