I have found out that certain pokemon cause error when you encounter therm.Regidrago,Regigeki,Glacstrier and Spectrier all cause this error when you encounter them.
Exception: NoMethodError
Message: undefined method `>' for nil:NilClass
PokeBattle_ActualScene:1156:in `showShadow?'
PokeBattle_ActualScene:2333:in `pbStartBattle'
PokeBattle_Battle:3320:in `pbStartBattleCore'
PokeBattle_Battle:3288:in `pbStartBattle'
PokemonField:1145:in `block (2 levels) in pbWildBattle'
PokemonField:679:in `pbSceneStandby'
PokemonField:1144:in `block in pbWildBattle'
PokemonField:1013:in `pbBattleAnimation'
PokemonField:1143:in `pbWildBattle'
PokemonField:1613:in `pbBattleOnStepTaken'
PokemonField:1634:in `pbOnStepTaken'
Game_Player_:507:in `update'
Walk_Run:99:in `update'
Scene_Map:104:in `block in update'
Scene_Map:101:in `loop'
Scene_Map:101:in `update'
Scene_Map:68:in `block in main'
Scene_Map:65:in `loop'
Scene_Map:65:in `main'
Main:45:in `mainFunctionDebug'
Main:24:in `block in mainFunction'
Compiler:66:in `pbCriticalCode'
Main:24:in `mainFunction'
Main:81:in `block (2 levels) in <main>'
Main:80:in `loop'