Improve Gen 4 Encore behavior

[scheibo]

Gen IV

• Encore should fail if the target did not make a move during its turn
  Due to flinch, full paralysis, etc.

Originally posted by @Marty-D in #2367 (comment)

This PR adds a test for this behavior, which already seems to work. However, it also seems to work regardless of generation, which makes me a little worried about what the correct behavior should be/whether the test is correct (for reference, this is the log from the test)?

@Marty-D - can you confirm that this test is testing the scenario you wanted fixed? Should the behavior be Gen 4 specific (in which case, what is the correct behavior for other gens so I can fix it?) or is this universal (in which case, I should just make the test run against the latest generation instead of scoped to gen(4))?

[Marty-D]

Oh, I guess my brief summary isn't very clear. In modern gens (5 onward), using a move, then being fully paralyzed, then being Encored has the Encore succeed on the move used the turn before. In Gen 4 (and earlier I presume, but I'll have to double check 2 and 3 later), that same situation has Encore fail.

[scheibo]

Great, I've updated the tests and now it makes more sense - the current behavior passes the new test case, and the Gen 4 (and possibly before) behavior is failing.

[scheibo]

So, looking at how I would fix this, here's what I'm thinking:

• the naive approach would be to look into unsetting lastMove in cases where the Pokemon didn't move. I don't think I'd want to do this because I imagine lastMove is used by several other things and this would likely affect their behavior.
• leverage moveThisTurnResult / moveThisTurnResult. This seems like it would be very convenient - just check if the moveLastTurnResult was successful before determing whether encore should fail. However, I think we also care about moveThisTurnResult because the lastMove could have been attempted this turn before the Encore user moves. However, while moveThisTurnResult has a warning about inspecting it in the middle of the turn, it seems like (!moveThisTurnResult && !moveLastTurnResult) makes my test pass? I'm a little worried about the case where moveThisTurnResult is undefined because the target is mid move? iunno, I'm still in the process of learning all this.

[Marty-D]

The naive approach might be the best way to do it; only problem could be Sketch. Here's a table of Gen 4 lastMove behaviour courtesy of UPC. I'll double check how Sketch works in HGSS in a bit.
Edit: Sketch does indeed succeed even if the last move was prevented.

If...	The last move used...	The last move called...	The last move used (for Sketch)...	The last move used by a Pokémon (for Copycat)...
Move is used	Is different for each Pokémon in battle	Is different for each Pokémon in battle	Is different for each Pokémon in battle	Is shared among all Pokémon in battle
Move fails, misses, or becomes ineffective	Is set	Is set	Is set [unsure for misses or becomes ineffective]	Is set
Move is Pursuit and a Pokémon is about to switch	Is set no matter whose attack segment it is [unsure]	Is set no matter whose attack segment it is [unsure]	Remains unchanged	Remains unchanged
Move is prevented from being used	Is reset to "no move"	Is reset to "no move"	Remains unchanged	Is reset to "no move"
Move can’t be used because it has zero PP	Is reset to "no move"	Is set	Is set	Is set
Move can’t be used because it has no target	Is reset to "no move"	Is set	Is set	Is set
Move is used by another move	Remains unchanged	Is set	Remains unchanged	Remains unchanged
Move had been taken by Snatch	Remains unchanged [unsure]	Remains unchanged if Pokémon is the move’s original user [unsure otherwise]	Is set no matter which Pokémon’s attack segment it is	N/A
Move had been taken by Magic Coat	Remains unchanged [unsure]	Is reset to "no move" while the move is used, but is then set to that move at the end of its original user’s attack segment	Remains unchanged	N/A
Move is a two-turnattack	Is set on both turns of use	Is set only on the second attack segment; is reset to "no move" otherwise	Is set only on the second attack segment; remains unchanged otherwise	Is set only on the second attack segment; remains unchanged otherwise
Move is Hyper Beam or an equivalent move	Is set only on the first attack segment [unsure if reset otherwise]	Is set only on the first attack segment; is reset to "no move" otherwise	Is set only on the first attack segment; remains unchanged otherwise	Is set only on the first attack segment; is reset to "no move" otherwise
Move is Bide	Is set on any attack segment of its use, but is reset to "no move" if it fails on the third attack segment of its use	Is set on any attack segment of its use, but is reset to "no move" if it fails on the third attack segment of its use	Is set on any attack segment of its use, but remains unchanged if it fails on the third attack segment of its use	Is set on any attack segment of its use, but is reset to "no move" if it fails on the third attack segment of its use
Move is Mimic, Sketch, or Transform	Is set	Is set	Is set	Is set
The Pokémon leaves the battle	Is reset to "no move"	Is reset to "no move"	Is reset to "no move"	Remains unchanged
The Pokémon used Baton Pass, Healing Wish, Lunar Dance, or U-turn to leave the battle	Is set to the corresponding move at end of new Pokémon’s attack segment	Is set to the corresponding move at end of new Pokémon’s attack segment	Is set to the corresponding move at end of new Pokémon’s attack segment	Is set to the corresponding move at end of new Pokémon’s attack segment
If an item is used with the Bag command	Remains unchanged	Remains unchanged	Remains unchanged	Remains unchanged
If the Run command is used and running is unsuccessful	Remains unchanged	Remains unchanged	Remains unchanged	Remains unchanged

[scheibo]

Hmm, that seems to be a more elaborate breakdown then PS currently tracks? To the best of my understanding, PS's Pokemon#lastMove corresponds to "The last move called" (I dont think we distinguish between called and The last move used" and not the "The last move used (for Sketch)..." either?), PS's Battle#lastMove seems like it would correspond to "The last move used by a Pokémon (for Copycat)...").

I've come up with two possible solutions to get the specific " Encore should fail if the target did not make a move during its turn (Due to flinch, full paralysis, etc.)" test case to pass:

• using move{This,Last}TurnResult: 6a65937
• resetting lastMove if the move is aborted: f99a01b

Neither of these encompass the entire table linked above (I think we would need 4 different fields, not just 2...), but seem like they would still be an incremental improvement over the current state?

[scheibo]

If I'm being honest with myself, I don't think I'm coming back to this. @Marty-D - you should add that table to the card for "Gen 4: Encore targeting in Double Battles" so that the next person looking into this knows about it.