Misc fixes for the usage of constants

Several improvements that will make it easier to edit some data
structures for everyone.

battle/core.asm

@@ -3454,7 +3454,7 @@ IsThePlayerPkmnTypesEffectiveAgainstOTPkmn: ; 3d618
 	ld bc, BASE_DATA_SIZE
 	call AddNTimes
 	ld de, EnemyMonType
-	ld bc, 2
+	ld bc, BASE_CATCH_RATE - BASE_TYPES
 	ld a, BANK(BaseData)
 	call FarCopyBytes
 	ld a, [BattleMonType1]

battle/effect_commands.asm

@@ -3881,11 +3881,11 @@ BattleCommand_Counter: ; 35813
 	ld de, StringBuffer1
 	call GetMoveData
 
-	ld a, [StringBuffer1 + 2]
+	ld a, [StringBuffer1 + MOVE_POWER]
 	and a
 	ret z
 
-	ld a, [StringBuffer1 + 3]
+	ld a, [StringBuffer1 + MOVE_TYPE]
 	cp SPECIAL
 	ret nc
 

engine/link.asm

@@ -740,7 +740,7 @@ Link_PrepPartyData_Gen1: ; 28499
 	ld hl, BaseData + BASE_TYPES
 	ld bc, BASE_DATA_SIZE
 	call AddNTimes
-	ld bc, 2
+	ld bc, BASE_CATCH_RATE - BASE_TYPES
 	ld a, BANK(BaseData)
 	call FarCopyBytes
 	pop bc

engine/stats_screen.asm

@@ -377,7 +377,7 @@ StatsScreen_InitUpperHalf: ; 4deea (13:5eea)
 	call .PlaceHPBar
 	xor a
 	ld [hBGMapMode], a
-	ld a, [CurBaseData]
+	ld a, [BaseDexNo]
 	ld [wd265], a
 	ld [CurSpecies], a
 	hlcoord 8, 0
@@ -401,7 +401,7 @@ StatsScreen_InitUpperHalf: ; 4deea (13:5eea)
 	hlcoord 9, 4
 	ld a, "/"
 	ld [hli], a
-	ld a, [CurBaseData]
+	ld a, [BaseDexNo]
 	ld [wd265], a
 	call GetPokemonName
 	call PlaceString