My apologies if this has already been reported or there is an available fix, but I was messing around with the new version of GameShark and every time I place a block, minecraft crashes. I made sure the only mods I had installed were Pixelmon and GameShark. Here is the crash report:

Minecraft Crash Report ----
// Who set us up the TNT?

Time: 12/30/16 1:12 AM
Description: Unexpected error

java.lang.NoClassDefFoundError: com/pixelmonmod/pixelmon/items/ItemBlock
at com.waterdude.gameshark.event.ClientEventHandler.onBlockRightClicked(ClientEventHandler.java:199)
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_59_ClientEventHandler_onBlockRightClicked_PlayerInteractEvent.invoke(.dynamic)
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90)
at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:185)
at net.minecraftforge.common.ForgeHooks.onRightClickBlock(ForgeHooks.java:1026)
at net.minecraft.client.multiplayer.PlayerControllerMP.func_187099_a(PlayerControllerMP.java:387)
at net.minecraft.client.Minecraft.func_147121_ag(Minecraft.java:1518)
at net.minecraft.client.Minecraft.func_184117_aA(Minecraft.java:2184)
at net.minecraft.client.Minecraft.func_184118_az(Minecraft.java:1961)
at net.minecraft.client.Minecraft.func_71407_l(Minecraft.java:1749)
at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:1055)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:371)
at net.minecraft.client.main.Main.main(SourceFile:124)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
Caused by: java.lang.ClassNotFoundException: com.pixelmonmod.pixelmon.items.ItemBlock
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 19 more
Caused by: java.lang.NullPointerException