The Franchise Supports Pearl!
There's some special news from the Pokemon Art Academy trailer.
Pokémon Art Academy has nothing to do with Pearlshipping at all, in fact it is related closer to the card game and the regular games. But somehow, even they know that Pikachu and Piplup are related. At the end of the E3 trailer featuring the game, it showed a collection of drawings in a collage, and the Pikachu and Piplup drawing was in front. Keep in mind this is the game canon. How would Pikachu and a random Sinnoh Pokémon, Piplup, be related to one another without Ash and Dawn? The artist clearly knew about Pikachu and Piplup either way which directly leads to Ash and Dawn.
Out of the 16 drawings in the final collage, the Pikachu and Piplup one was the only one to be a drawing of two, not just one, Pokémon. And they're not just in any position. Pikachu and Piplup are basically high fiving in the drawing! Now I don't know if it was a staff or a fan that drew it but it was likely a staff member working on the game. Without Pearlshipping or Dawn, Pikachu and Piplup being THAT close is impossible. This can only mean that Pearlshipping (anime canon), or the Pokémon of the 'chosen' couple to say the least, plays a strong enough role in the franchise* to be an example drawing of the *game canon Pokémon Art Academy.