Document more Beat Up-related bugs

Two bugs related to not raising the substitute when it should, one bug
related to not running king's rock when it should, and the other related
to running king's rock when it shouldn't. Fun.

docs/bugs_and_glitches.md

@@ -15,6 +15,8 @@ These are known bugs and glitches in the original Pokémon Crystal game: code th
 - [A Pokémon that fainted from Pursuit will have its old status condition when revived](#a-pokémon-that-fainted-from-pursuit-will-have-its-old-status-condition-when-revived)
 - [Lock-On and Mind Reader don't always bypass Fly and Dig](#lock-on-and-mind-reader-dont-always-bypass-fly-and-dig)
 - [Beat Up can desynchronize link battles](#beat-up-can-desynchronize-link-battles)
+- [Beat Up may fail to raise substitute](#beat-up-may-fail-to-raise-substitute)
+- [Beat Up may trigger King's Rock even if it failed](#beat-up-may-trigger-kings-rock-even-if-it-failed)
 - [Present damage is incorrect in link battles](#present-damage-is-incorrect-in-link-battles)
 - ["Smart" AI encourages Mean Look if its own Pokémon is badly poisoned](#smart-ai-encourages-mean-look-if-its-own-pokémon-is-badly-poisoned)
 - [AI makes a false assumption about `CheckTypeMatchup`](#ai-makes-a-false-assumption-about-checktypematchup)
@@ -339,6 +341,82 @@ This is a bug with `BattleCommand_BeatUp` in [engine/battle/move_effects/beat_up
 **Fix:** Change `cp [hl]` to `cp c`.
 
 
+## Beat Up may fail to raise substitute
+
+*Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.*  
+(Only the fixes denoted with "breaking" will actually break compatibility, the others just affect what's shown on the screen with the patched game)
+
+This is a bug in `BattleCommand_EndLoop` in [engine/battle/effect_commands.asm](/engine/battle/effect_commands.asm) that prevents the rest of the move's effect from being executed if the player or enemy only has one mon in their party while using Beat Up.
+
+It prevents the substitute from being raised and the King's Rock from working.
+
+```asm
+.only_one_beatup
+	ld a, BATTLE_VARS_SUBSTATUS3
+	call GetBattleVarAddr
+	res SUBSTATUS_IN_LOOP, [hl]
+	call BattleCommand_BeatUpFailText
+	jp EndMoveEffect
+```
+
+**Fix (breaking):** Replace the last two lines with `ret`.  
+**Fix (cosmetics):** Call `BattleCommand_RaiseSub` before the `jp`.
+
+There's a similar oversight in `BattleCommand_FailureText` in [engine/battle/effect_commands.asm](/engine/battle/effect_commands.asm) that will prevent the substitute from being raised if Beat Up is protected against.
+
+```asm
+	cp EFFECT_MULTI_HIT
+	jr z, .multihit
+	cp EFFECT_DOUBLE_HIT
+	jr z, .multihit
+	cp EFFECT_POISON_MULTI_HIT
+	jr z, .multihit
+	jp EndMoveEffect
+
+.multihit
+	call BattleCommand_RaiseSub
+	jp EndMoveEffect
+```
+
+**Fix:** Check for `EFFECT_BEAT_UP` as well.
+
+
+## Beat Up may trigger King's Rock even if it failed
+
+*Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.*
+
+This is a bug in how `wAttackMissed` is never set by BeatUp, even when none of the 'mon have been able to attack (due to being fainted or having a status effect), the King's Rock may activate.
+
+This bug can be fixed in a plethora of ways, but the most straight-forward would be in `BattleCommand_BeatUpFailText` in [engine/battle/move_effects/beat_up.asm](/engine/battle/move_effects/beat_up.asm), as that's always ran before the king's rock effect.
+
+```asm
+BattleCommand_BeatUpFailText: ; 355b5
+; beatupfailtext
+
+	ld a, [wBeatUpHitAtLeastOnce]
+	and a
+	ret nz
+
+	jp PrintButItFailed
+```
+
+**Fix:**
+
+```asm
+BattleCommand_BeatUpFailText: ; 355b5
+; beatupfailtext
+
+	ld a, [wBeatUpHitAtLeastOnce]
+	and a
+	ret nz
+
+	inc a
+	ld [wAttackMissed], a
+
+	jp PrintButItFailed
+```
+
+
 ## Present damage is incorrect in link battles
 
 *Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.*