The latest episode of Pokemon Sun and Moon: The Series that aired today in Japan had a surprising shoutout to two of Ash's oldest friends. The episode showed Ash and his current companions going to see a concert hosted by a local DJ and his Alolan Dugtrio. Team Rocket is also at the concert, trying to sell wigs to concertgoers. Although wigs featuring the blonde hairstyles of the Alolan Dugtrio are popular purchases, Team Rocket's knockoff wigs fail to attract any buyers.
However, Team Rocket's booth does feature a big Easter egg for fans. Two of the wigs for sale look based off of Brock and May's hair designs. Brock was Ash's most frequent travel companion, although the pair separated in 2013 so Brock could become a Pokemon Doctor. May was one of Ash's companions in the Hoenn region and last made a brief appearance back in 2008 in a Pokemon Contest tournament in the Sinnoh region.
As you can see below, several other characters from the anime were also referenced in the clever Easter egg.
It's nice to see the current Pokemon anime referencing Ash's companions, especially as the show has moved away from referencing ANY of Ash's past adventures when he travels to a new region. Most of Ash's older Pokemon haven't been seen in years and the anime even skipped the traditional "reset" episode where Ash drops off his new Pokemon at Professor Oak's lab before leaving to a new region.
However, it is the 20th anniversary of the anime, so we could see more Easter eggs or cameos from old characters soon. Ash's Charizard and Butterfree are both set to appear in the next Pokemon movie out this summer. Could Brock or Misty's return follow? We'll have to wait and keep watching the Pokemon anime to find out!