After Sunny Day is used, Solar Beam and Solar Blade attack immediately after charging up, which is normal. However, on a new turn, I don't get to pick a move and Solar Beam gets executed again. Maybe the "it's sunny day?" Condition makes the "charging" Script to allow solar beam to be executed immediately, but the "using move after charging" Script isn't included in the "sunny day" Condition, so it gets executed again. IDK please help.
EDIT:
This is a quick fix that I tested with Solar Beam, Solar Blade, Fly (2 turn semi-invulnerability move unrelated to Sunny Day) and Skull Bash (2 turn move unrelated to Sunny Day).
These moves were tested with both Sunny weather and no weather.
I have no idea what coding issues this might bring up (I think none), and I hope your PC doesn't overheat with Sunny day. Again, it's just a temporary fix, as I'm a noob at coding.
EDIT: Found a new bug. Using a battle item (ex: xAttack) on a pokemon with that stat maxed opens the party screen, and if I choose another Pokemon it gives an error:
Within the same issue, if a battle item is used in a double battle and I choose the boost the pokemon on the right, it ends up boosting the right side enemy.