Some pages from chapter 1 of the spinoff manga have leaked. Keep in mind that this is not the full chapter, so any weird jumps in the story are just a result of missing pages:
https://i.imgur.com/8Kd6CyF.jpg
Satoshi: I want to meet Lugia as well!!
Pikachu: Pika!!
Satoshi: Meet AND battle it!!
Largo: Heheh... But you know, Lugia isn't the only one you might meet...
Largo: There's apparently someone else as well...
Largo: You see, there's another legend connected to Fura City...
Largo: A legend about a mythical Pokémon!!
Satoshi: Really?! I want to meet it.
Professor: Ho ho! I can show it to you!
Satoshi: Whoa, where did you come from?!
Professor: I am professor Sanzashi.
Sanzashi: And this is my assistant Eleboo!!
Eleboo: Ele!!
Sanzashi: If you come to my pavilion, you can see that Pokémon!
Sanzashi: I made the pavillion because I wanted to show it to everyone, since this is a festival and all,
Sanzashi: but nobody's coming to see it...
Largo: This is starting to look kinda fishy...
Satoshi: I want to see that mythical Pokémon!
Sanzashi: Really?! In that case, step right this way!!
Largo: Geez, Satoshi.
Pikachu: Pikaa.
Sanzashi: Ho ho.
Sanzashi: Look.
Sanzashi: Here it is!
Largo: THIS SERIOUSLY SMELLS LIKE TROUBLE!!
Largo: I... Is this really a good idea?
Satoshi: It's fine!
Satoshi: Man, I'm so excited.
Satoshi: Pardon the intrusion!!
Largo: Hey...
Largo: Your partner really loves Pokémon, doesn't he?
Pikachu: Pikaa.
Satoshi: WHOA.
Pikachu: Pika!!
Largo: Satoshi, what's wrong?
https://i.imgur.com/b82ruke.jpg
Satoshi: It looked all worn-down and tattered from the outside, but the inside is amazing!
Sanzashi: Ho ho.
Sanzashi: Put these on!
Satoshi: Whoa.
Satoshi: These are really cool.
Pikachu: Pika.
Sanzashi: This is VR gear. Now that you've put it on...
Sanzashi: ...you can experience the legend on Fura City first-hand!
Sanzashi: Have fun!
Satoshi. WHOOOOOOAAA!
https://i.imgur.com/8QJp82h.jpg
Satoshi: Technology is incredible!!
Sanzashi: This is Fura City in the ancient past!!
Satoshi: Huh? I can hear the professor's voice...
Sanzashi: You're hearing me through the VR gear.
Satoshi: We can feel the wind and smell the smells... it's like we're actually here.
Largo: Yeah.
Sanzashi: Ho ho. That's how amazing my technology is!
Maril: Luri.
Pichu: Pichu.
Satoshi: Hey, wild Pokémon.
Satoshi: THEY WENT STRAIGHT THROUGH ME.
Sanzashi: Of course. This is just VR!
Sanzashi: At this point in time, something happened!
Satoshi: Huh?
https://i.imgur.com/g58xXK1.jpg
Sanzashi: A VOLCANIC ERUPTION!!
Satoshi: Whoa!
Satoshi: Seriously?
Largo: I'm scared...
Sanzashi: The sudden eruption caused thunderclouds to form,
https://i.imgur.com/wJiy76z.jpg
Sanzashi: and a bolt of lightning struck the crater!
Sanzashi: And the combination of that lightning bolt and the volcanic fire...
Sanzashi: ...caused a massive explosion...
Largo: Eeek!
Satoshi: Whoa!
Sanzashi: ...that led to the creation of...
Sanzashi: ...the mythical Pokémon...
Sanzashi: ZERAORA!!
https://i.imgur.com/xVP9lxR.jpg
Satoshi: Whoa, there's the city!
Largo: Oh, that's the power plant!!
Satoshi: Are you familiar with it, Largo?
Largo: Yeah. It's not in use anymore, though, and is all worn down.
Sanzashi: Zeraora and the Pokémon lived in peace and prosperity...
Sanzashi: ...next to the power plant!
Satoshi: That's great.
Satoshi: Is that the end of the story?
Sanzashi: No!
Sanzashi: Eventually THEY showed up!
Sanzashi: THE POKÉMON HUNTERS!!
Male hunter: Heh heh...
https://i.imgur.com/4sT9INf.jpg
Male hunter: The Pokémon here all look full of energy!!
Female hunter: We can sell them high!
Satoshi: I can't believe these guys!
Pikachu: Pika!
Male hunter: Whoa.
Zeraora: Rrrr...
Largo: Zeraora.
Male hunter: This is a rare Pokémon!
Female hunter: Rare, huh? In that case, we'll definitely get it!
https://i.imgur.com/zFZGk6P.jpg
Male hunter: Fine, have it your way!
Female hunter: But this isn't over.
Pichu: Pichu.
Togepy: Chokkiprii.
Zeraora: Rrrr.
Pichu: Pichu.
Satoshi: Zeraora is really strong, huh?
Satoshi: Now I want to battle it more than ever!!
Pikachu: Pika!
Narration box: The Pokémon Hunter base
Boss: What?
Boss: A rare Pokémon?
Male hunter: Yes sir, Agai-san. We met it near the power plant...
Female hunter: It was crazy strong.
Agai: Well, let's go grab it, then.
Agai: After all, that's what Pokémon Hunters do...
Agai: Isn't that right, Bangiras?
Narration: Who is this man...?! It feels like an intense battle is coming up...!!
Narration: To be continued in the July issue.