More battle code cleanup.

- Use more substatus constants.
- Reformat some code to be more atomic.
- Add constants for unused status prevention held item effects.
- Remove pointless or redundant comments.

constants/battle_constants.asm

@@ -1,6 +1,8 @@
 MAX_LEVEL EQU 100
 NUM_MOVES EQU 4
 
+REST_TURNS EQU 2
+
 ATTACK EQU 0
 DEFENSE EQU 1
 SPEED EQU 2
@@ -110,6 +112,7 @@ SUBSTATUS_UNLEASH      EQU 0
 SUBSTATUS_CANT_RUN     EQU 7
 SUBSTATUS_DESTINY_BOND EQU 6
 SUBSTATUS_LOCK_ON      EQU 5
+SUBSTATUS_TRANSFORMED  EQU 3
 SUBSTATUS_TOXIC        EQU 0
 
 ; environmental
@@ -119,6 +122,7 @@ SCREENS_SAFEGUARD    EQU 2
 SCREENS_SPIKES       EQU 0
 
 ; weather
+WEATHER_NONE EQU 0
 WEATHER_RAIN EQU 1
 WEATHER_SUN EQU 2
 WEATHER_SANDSTORM EQU 3