I'm not a Java expert so I hope someone can gleam the problem from this file. I have 8 gigs of available RAM and I'm running what I believe are the correct versions of the game.

---- Minecraft Crash Report ----
// Uh... Did I do that?

Time: 6/19/19 12:00 AM
Description: There was a severe problem during mod loading that has caused the game to fail

net.minecraftforge.fml.common.LoaderExceptionModCrash: Caught exception from Pixelmon (pixelmon)
Caused by: java.lang.NoClassDefFoundError: net/minecraftforge/common/util/ITeleporter
	at java.lang.Class.getDeclaredMethods0(Native Method)
	at java.lang.Class.privateGetDeclaredMethods(Class.java:2701)
	at java.lang.Class.privateGetPublicMethods(Class.java:2902)
	at java.lang.Class.getMethods(Class.java:1615)
	at net.minecraftforge.fml.common.eventhandler.EventBus.register(EventBus.java:81)
	at com.pixelmonmod.pixelmon.CommonProxy.init(CommonProxy.java:129)
	at com.pixelmonmod.pixelmon.client.ClientProxy.init(ClientProxy.java:158)
	at com.pixelmonmod.pixelmon.Pixelmon.init(Pixelmon.java:132)
	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:497)
	at net.minecraftforge.fml.common.FMLModContainer.handleModStateEvent(FMLModContainer.java:606)
	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:497)
	at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91)
	at com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:150)
	at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:76)
	at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:399)
	at com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:71)
	at com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116)
	at com.google.common.eventbus.EventBus.post(EventBus.java:217)
	at net.minecraftforge.fml.common.LoadController.sendEventToModContainer(LoadController.java:253)
	at net.minecraftforge.fml.common.LoadController.propogateStateMessage(LoadController.java:231)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:497)
	at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91)
	at com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:150)
	at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:76)
	at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:399)
	at com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:71)
	at com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116)
	at com.google.common.eventbus.EventBus.post(EventBus.java:217)
	at net.minecraftforge.fml.common.LoadController.distributeStateMessage(LoadController.java:148)
	at net.minecraftforge.fml.common.Loader.initializeMods(Loader.java:719)
	at net.minecraftforge.fml.client.FMLClientHandler.finishMinecraftLoading(FMLClientHandler.java:352)
	at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:534)
	at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:377)
	at net.minecraft.client.main.Main.main(SourceFile:123)
	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:497)
	at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
	at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
Caused by: java.lang.ClassNotFoundException: net.minecraftforge.common.util.ITeleporter
	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)
	... 49 more
Caused by: java.lang.NullPointerException


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

-- System Details --
Details:
	Minecraft Version: 1.12.2
	Operating System: Windows 10 (amd64) version 10.0
	Java Version: 1.8.0_51, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 2463786736 bytes (2349 MB) / 3063939072 bytes (2922 MB) up to 3063939072 bytes (2922 MB)
	JVM Flags: 3 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx3072M -Xms3072m
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	FML: MCP 9.42 Powered by Forge 14.23.1.2560 6 mods loaded, 6 mods active
	States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored

	| State | ID                | Version      | Source                                         | Signature                                |
	|:----- |:----------------- |:------------ |:---------------------------------------------- |:---------------------------------------- |
	| UCHI  | minecraft         | 1.12.2       | minecraft.jar                                  | None                                     |
	| UCHI  | mcp               | 9.42         | minecraft.jar                                  | None                                     |
	| UCHI  | FML               | 8.0.99.99    | forge-1.12.2-14.23.1.2560.jar                  | e3c3d50c7c986df74c645c0ac54639741c90a557 |
	| UCHI  | forge             | 14.23.1.2560 | forge-1.12.2-14.23.1.2560.jar                  | e3c3d50c7c986df74c645c0ac54639741c90a557 |
	| UCHI  | mercurius_updater | 1.0          | MercuriusUpdater-1.12.2.jar                    | None                                     |
	| UCHE  | pixelmon          | 2.6.2        | PixelmonGenerations-1.12.2-2.6.2-universal.jar | None                                     |

	Loaded coremods (and transformers): 
	GL info: ' Vendor: 'Intel' Version: '4.5.0 - Build 23.20.16.4973' Renderer: 'Intel(R) HD Graphics 530'

I'll give that a try and get back to you.