HELP ME FORGE!

---- Minecraft Crash Report ----
// Oops.

Time: 11/4/13 3:38 AM
Description: Exception in server tick loop

java.lang.NoSuchMethodError: net.minecraftforge.common.EnumHelper.addToolMaterial(Ljava/lang/String;IIFFI)Lnet/minecraft/item/Item;
	at pixelmon.Pixelmon.<clinit>(Pixelmon.java:60)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Unknown Source)
	at cpw.mods.fml.common.FMLModContainer.constructMod(FMLModContainer.java:457)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:74)
	at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
	at com.google.common.eventbus.EventBus.dispatch(EventBus.java:313)
	at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:296)
	at com.google.common.eventbus.EventBus.post(EventBus.java:267)
	at cpw.mods.fml.common.LoadController.sendEventToModContainer(LoadController.java:194)
	at cpw.mods.fml.common.LoadController.propogateStateMessage(LoadController.java:174)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:74)
	at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
	at com.google.common.eventbus.EventBus.dispatch(EventBus.java:313)
	at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:296)
	at com.google.common.eventbus.EventBus.post(EventBus.java:267)
	at cpw.mods.fml.common.LoadController.distributeStateMessage(LoadController.java:105)
	at cpw.mods.fml.common.Loader.loadMods(Loader.java:509)
	at cpw.mods.fml.server.FMLServerHandler.beginServerLoading(FMLServerHandler.java:99)
	at cpw.mods.fml.common.FMLCommonHandler.onServerStart(FMLCommonHandler.java:350)
	at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:69)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:445)
	at net.minecraft.server.ThreadMinecraftServer.run(SourceFile:583)


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- System Details --
Details:
	Minecraft Version: 1.6.4
	Operating System: Windows 8 (x86) version 6.2
	Java Version: 1.7.0_11, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 358723264 bytes (342 MB) / 415629312 bytes (396 MB) up to 415629312 bytes (396 MB)
	JVM Flags: 2 total; -Xmx410m -Xms410m
	AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	Suspicious classes: FML and Forge are installed
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	FML: MCP v8.11 FML v6.4.3.883 Minecraft Forge 9.11.0.883 5 mods loaded, 5 mods active
	mcp{8.09} [Minecraft Coder Pack] (minecraft.jar) Unloaded->Constructed
	FML{6.4.3.883} [Forge Mod Loader] (forge.jar) Unloaded->Constructed
	Forge{9.11.0.883} [Minecraft Forge] (forge.jar) Unloaded->Constructed
	customnpcs{0.8} [CustomNpcs] (CustomNPCs_1.6.2.zip) Unloaded->Constructed
	pixelmon{2.3.1} [Pixelmon] (Pixelmon 2.3.1.zip) Unloaded
	Profiler Position: N/A (disabled)
	Is Modded: Definitely; Server brand changed to 'fml,forge'
	Type: Dedicated Server (map_server.txt)