Titan Level: 20
Path to Open Sky Titan
The Open Sky Titan can be found in western Paldea, so if you started by leaving out the east gate as per Arven’s suggestion, you’re going to want to do some backtracking to get back to Mesagoza and then head out from the west gate this time around. It’s also a good time to take on the Cortondo Gym, if you haven’t done that already.
Make your way to Cortondo, which is pretty easy, and then leave from the western exit. Follow the road leading out of town up a zigzaggy cliffside, all the way over to a bridge across a river. Keep following the path until you find a Pokémon Center and some windmills in the background.
You can find a Thunder Stone on top of one of the windmills, which might be helpful if you want to evolve Pikachu into Raichu or Eevee into Jolteon (or Eelektrik into Eelektross, but that probably won’t be something to consider this early). There’s also TM113 Tailwind on top of another windmill.
From here, continue to the north, alongside those windmills, but when you reach another bridge crossing a river, ignore the bridge and instead take a left. You’ll need to climb a rocky hill with boulders barreling down from it. Ride on your Koraidon/Miraidon and try to dodge the boulders, but even if they hit you, they’ll just knock you back a little bit.
vs. Open Sky Titan
It’s a good idea to be healed before you get to the top of the mountain, because as soon as you arrive at the top, you’ll be attacked by the Open Sky Titan—a giant Bombirdier!
This Bombirdier is a Flying/Dark-type Pokémon, so keep that in mind, although it doesn’t have any Dark-type moves. It will hit fairly hard with its Flying-type moves, such as Pluck, and it also packs Rock Throw to do some Rock-type damage.
After you’ve weakened it down to about 10% of its maximum HP, the battle will end and it will crash into the nearby mountain and eat some Herba Mystica. You’ll then be joined by Arven and will challenge the Bombirdier once again.
Headbutt
Rock Throw-
Rock Polish
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Smack Down
Arven uses a Nacli Lv. 19 and it does a pretty good job at taking hits and doing damage, so it should be fine, and any hit that Bombirdier spends on Nacli is a hit you don’t have to worry about taking yourself. That being said, Bombirdier does receive a boost to its stats, so be on guard, although you should be able to take it down in a similar way as during the first fight.
Once you’ve beaten Bombirdier, you’ll enter the cave, obtain the Herba Mystica, and hear a bit more of Arven’s story. You’ll then be rewarded with the ability for your Koraidon/Miraidon to swim on water, which is very helpful for letting you traverse the land- err, the water!
This can help you cross various lakes and rivers, but keep in mind you might not be able to get out of rivers until you can high jump or climb, so you may need to wind up following the stream until you find an exit (or just fast traveling). You can also swim around in the Paldean sea and find a lot of Water-type Pokémon out there, but they might be a bit high level for you, depending on where you go, so be careful.
Catch Titan Bombirdier
After you’ve defeated Titan Bombirdier, you can find it in the overworld down the mountain where you fought it in and you can battle against it by pressing A next to it. If you catch it, it will have a special Mark that grants it the title “Bombirdier the Former Titan” when sent out in battle, plus it has very good stats (almost-perfect 30 IVs in every stat) and its useful Hidden Ability, Rocky Payload, making it quite useful.
Where to Go Next
If you’re following the Path of Legends storyline, the next titan, the Lurking Steel Titan, is at a bit higher of a level, and you can find it in eastern Paldea, to the north of Levincia. However, if you’re following the recommended path, the Team Star Dark Base is right in the area and would be perfect for you to challenge at this point, so it’s a good idea to check it out.