[Scripting Question] Passive Item Effect in Battle

[SeedotBrain]

I'm looking to have a key item the player gets as a reward for completing a quest that permanently increases the power of bug-type moves by a little. Like a Silver Powder, but that is always in effect, and doesn't need to be held by a Pokemon in battle. Does anyone know if there is a way I can make this work?
If so, I was also hoping to be able to use the same idea to make a similar item that has the effect of an Amulet Coin. So the player's prize money from battles will double if they just have this item in their bag, rather than having a Pokemon hold it in battle.

 

[burningplain]

Money is easy. In the Script Section Battle_StartandEnd, find this section of code:

def pbGainMoney
    return if !@internalBattle || !@moneyGain
    # Money rewarded from opposing trainers
    if trainerBattle?
      tMoney = 0
      @opponent.each_with_index do |t, i|
        tMoney += pbMaxLevelInTeam(1, i) * t.base_money
      end
      tMoney *= 2 if @field.effects[PBEffects::AmuletCoin]
      tMoney *= 2 if @field.effects[PBEffects::HappyHour]
      oldMoney = pbPlayer.money
      pbPlayer.money += tMoney
      moneyGained = pbPlayer.money - oldMoney

In between these two lines

tMoney *= 2 if @field.effects[PBEffects::HappyHour]
      oldMoney = pbPlayer.money

add

tMoney *= 2 if $bag.has?(:LEMONADE)

With Lemonade being a placeholder for your key item. You can learn how to make key items on the wiki if you need to.

For the damage item, go to Move_UsageCalculations and find the line of code that says:

def pbCalcDamageMultipliers(user, target, numTargets, type, baseDmg, multipliers)

Underneath it put

if ($bag.has?(:SILVERPOWDER) && type == :BUG)
       multipliers[:base_damage_multiplier] *= 1.2
    end

With Silver Powder being a place holder for your item.

 

[SeedotBrain]

Amazing! Thank you for all of the help!
Unfortunately, they both returned errors when trying to implement them. :/ I maybe should have mentioned that I'm using version 1.18. Do you think that might be where the problem is? And if you think there are any changes that can be made to make the codes usable in the version my game is using? I included the errors below, in case that's helpful.
Any advice would be greatly appreciated! And thank you again for all of the amazing help you've given me already! :)

The error for the Amulet Coin item was:

[Pokémon Essentials version 18.1]
Exception: RuntimeError
Message: Script error within event 13 (coords 16,3), map 137 (Cascade Park Gym):
Exception: NoMethodError
Message: Battle_StartAndEnd:349:in `pbGainMoney'undefined method `has?' for nil:NilClass

***Full script:
pbTrainerBattle(:LEADER_Norma,"Norma",_I("Aww, boo!"),false,0)

Backtrace:
Interpreter:197:in `pbExecuteScript'
Battle_StartAndEnd:417:in `pbEndOfBattle'
Battle_StartAndEnd:330:in `pbBattleLoop'
Battle_StartAndEnd:300:in `pbStartBattleCore'
Battle_StartAndEnd:258:in `pbStartBattle'
Sky Battle:400:in `pbTrainerBattleCore'
Sky Battle:399:in `pbSceneStandby'
Sky Battle:401:in `pbTrainerBattleCore'
Sky Battle:398:in `pbBattleAnimation'
Sky Battle:398:in `pbTrainerBattleCore'

Backtrace:
Interpreter:246:in `pbExecuteScript'
Interpreter:658:in `command_111'
Interpreter:272:in `execute_command'
Interpreter:155:in `update'
Interpreter:102:in `loop'
Interpreter:158:in `update'
Scene_Map:162:in `follow_update'
Scene_Map:160:in `loop'
Scene_Map:169:in `follow_update'
Follower_Main:1325:in `update'

And the error for the Silver Powder item was:

[Pokémon Essentials version 18.1]
Exception: NoMethodError
Message: undefined method `has?' for nil:NilClass

Backtrace:
Move_Usage_Calculations:252:in `pbCalcDamage'
Battler_UseMove:619:in `pbProcessMoveHit'
Battler_UseMove:611:in `each'
Battler_UseMove:611:in `pbProcessMoveHit'
Battler_UseMove:422:in `pbUseMove'
Battler_UseMove:420:in `each'
Battler_UseMove:420:in `pbUseMove'
Battler_UseMove:59:in `pbProcessTurn'
Battler_UseMove:58:in `logonerr'
Battler_UseMove:58:in `pbProcessTurn'