Until April 16, 2023 at 4:59pm PDT / 7:59pm EDT (23:59 UTC), you’ll be able to fight against a fearsome mixed attacking Johtonian Typhlosion in 7-star Tera Raids in Pokémon Scarlet & Violet. This Typhlosion is always a Ghost Tera Type during the raids, so while it might not quite be Hisuian Typhlosion, it comes close. As with previous 7-star Tera Raid Events, it has the Mightiest Mark, which grants it the “Typhlosion the Unrivaled” title when sent out in battle.
Before you’ll be able to find it in Tera Raid Dens, you’ll first need to have unlocked 6-star Raids (which requires beating the game), and then it’ll appear in the Black Tera Raid Crystals on the map similar to the 6-star Raids. Even if you don’t have it unlocked, you can still join other players if they have unlocked it.
According to Serebii.net’s coverage, it knows the moves Eruption, Shadow Ball, Play Rough, and Earthquake, making it a bit of a mixed attacker. It also uses Sunny Day as an extra move, making Eruption hit that much harder in the earlier stages of the fight.
After beating it, you’ll be able to catch it, although you can only catch it once, regardless of how many times you fight it. You can still fight it repeatedly for its rewards, though, which include a good amount of Exp. Candies L and XL, Ghost Tera Shards, Calciums, and even a chance at getting an Ability Patch—although you’re guaranteed to get one as well as TM114 Shadow Ball the first time you defeat Typhlosion.
Additionally, this Typhlosion is always super small, meaning you can take it to the person that judges a Pokémon’s size in western Mesagoza and she’ll give the Typhlosion the Mini Mark, granting it another title: Typhlosion the Teeny. Since getting Pokémon with the Mini Mark is quite rare, this is a nice bonus, although its size doesn’t affect its stats, don’t worry—they’re perfect across the board (for a Typhlosion) anyway.
This is the first of two opportunities you’ll have to fight Typhlosion, as it will return the following weekend, from April 20, 2023 at 5:00pm PDT / 8:00pm EDT (April 21 at 00:00 UTC) through April 23, 2023 at 4:59pm PDT / 7:59pm EDT (23:59 UTC). You can still only catch it once per game, regardless of which weekend you fight it on, though.