The tournament brings together all (or almost all) the strongest Pokémon trainers in the world, so why weren't Ethan, Brendan, and Lucas invited?
Ethan defeated all the gym leaders of Johto and Kanto, became the new champion of both regions by defeating Lance and the Elite Four, and defeated Red. He also prevented Team Rocket's return.
Brendan prevented Groudon and Kyogre from destroying the world, defeated Team Magma (or Aqua, depending on which version you consider canonical), and after that became the new Hoenn champion by defeating Steven (or Wallace).
Lucas prevented Team Galactic and its leader from destroying the world and recreating it without emotions, freed Mesprit, Azelf, and Uxie, then he defeated Cynthia, considered one of the strongest trainers currently, becoming the new Sinnoh champion. Correct me if I'm wrong, but didn't he also defeat Giratina? It's been years since I played Pokémon Platinum, I don't remember exactly.
All three meet the requirements to be invited; they all have legendary feats as great as the current participants. Is there any explanation in the lore for why they weren't invited?
by Significant-Ad-2786