How would Future Sight interact with Psychic Terrain that is set up after the move was used?

Question

I was answering This Question and since the new player Pokémon doesn't affect the power of Future Sight, what if the new player Pokemon was Tapu Lele or Indeedee? Would the Psychic Terrain generated by Psychic Surge give Future Sight the 30% (Or 50% If you're in Gen 7) boost?

I've already looked at the Bulbapedia entry, and it just says that "Affected Pokémon get the power of their Psychic-Type moves boosted by 50%" (30% in the Gen 8 update.) Since the original user of Future Sight is not affected by the Psychic Terrain, since they're benched.

I would like some evidence, like a replay or somewhere where it directly addresses this scenario.

Thank you.

Comments

I don’t use showdown so I can’t get a re play but would just testing this in Scarlet  be sufficient for an answer?

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Sure. Just make sure to write down exactly what and how you're testing and put it in the answer, so we can be sure there are no other factors at play

Answer 1

I used 2 Pokemon for this test. A Latias with future sight and a Calyrex ice rider with psychic terrain. Then I did the following 3 tests all against the same wild duraldon so I wouldn’t have to worry about the duralodon having different Ivs and natures

1. On this attempt I just used Future sight no terrain and it did about 52 percent to duraldon

2. On this attempt I used future sight switched to Calyrex and used psychic terrain. This time duraldon took closer to 75 percent of its health.

3. For this attempt I started with Calyrex used Psychic terrain and switched to Latias.
   Then on the last turn of psychic terrain I used future sight. That future sight did a little over 50 percent to duraldon.

From this I’ve concluded that Future sight does more dammage if it lands while psychic terrain is on the field