Delphox with the Mightiest Mark is coming to Pokémon Scarlet and Pokémon Violet black crystal Tera Raid Battles! You can try putting a stop to Delphox’s Mystical Fire from Thursday, July 6, 2023, at 5:00 p.m. to Sunday, July 9, 2023, at 4:59 p.m. PDT, then again from Thursday, July 13, 2023, at 5:00 p.m. to Sunday, July 16, 2023, at 4:59 p.m. PDT. Delphox cannot normally be encountered in Paldea, and the Delphox appearing during this event has Fairy as its Tera Type. Be prepared—this Pokémon is a formidable foe, and it’s got the Mightiest Mark to prove it!

What is the strategy for this one? Any suggestions?

https://www.pokemon.com/us/pokemon-news/delphox-is-coming-to-tera-raid-battles