Use constants for bit/set/res more

engine/events/battle_tower/battle_tower.asm

@@ -254,7 +254,7 @@ RunBattleTowerTrainer: ; 17024d
 	farcall HealParty
 	ld a, [wBattleResult]
 	ld [wScriptVar], a
-	and a
+	and a ; WIN?
 	jr nz, .lost
 	ld a, BANK(sNrOfBeatenBattleTowerTrainers)
 	call GetSRAMBank

engine/events/bug_contest/display_stats.asm

@@ -7,7 +7,7 @@ DisplayCaughtContestMonStats: ; cc000
 	ld hl, wOptions
 	ld a, [hl]
 	push af
-	set 4, [hl]
+	set NO_TEXT_SCROLL, [hl]
 
 	hlcoord 0, 0
 	ld b, 4

engine/events/celebi.asm

@@ -325,15 +325,15 @@ CelebiEvent_SetBattleType: ; 49bf3
 
 CheckCaughtCelebi: ; 49bf9
 	ld a, [wBattleResult]
-	bit 6, a
+	bit BATTLERESULT_CAUGHT_CELEBI, a
 	jr z, .false
-	ld a, $1
+	ld a, TRUE
 	ld [wScriptVar], a
 	jr .done
 
 
 .false
-	xor a
+	xor a ; FALSE
 	ld [wScriptVar], a
 
 .done