---- Minecraft Crash Report ----

WARNING: coremods are present:
SpongeCoremod (spongeforge-1.8.9-1890-4.2.0-BETA-1547.jar)
Contact their authors BEFORE contacting forge

// On the bright side, I bought you a teddy bear!

Time: 13/07/16 09:16
Description: Exception in server tick loop

net.minecraftforge.fml.common.LoaderException: java.lang.AbstractMethodError: ninja.leaping.permissionsex.sponge.PermissionsExPlugin.getDefaultData()Lorg/spongepowered/api/service/permission/SubjectData;
at net.minecraftforge.fml.common.LoadController.transition(LoadController.java:162)
at net.minecraftforge.fml.common.Loader.serverStarted(Loader.java:801)
at net.minecraftforge.fml.common.FMLCommonHandler.handleServerStarted(FMLCommonHandler.java:289)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:443)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.AbstractMethodError: ninja.leaping.permissionsex.sponge.PermissionsExPlugin.getDefaultData()Lorg/spongepowered/api/service/permission/SubjectData;
at net.minecraft.command.ServerCommandManager.registerDefaultPermissions(SourceFile:128)
at net.minecraft.command.ServerCommandManager.registerCommandsList(SourceFile:139)
at net.minecraft.command.ServerCommandManager.registerLowPriorityCommands(SourceFile:145)
at org.spongepowered.mod.SpongeMod.onServerStarted(SpongeMod.java:272)
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.EventSubscriber.handleEvent(EventSubscriber.java:74)
at com.google.common.eventbus.SynchronizedEventSubscriber.handleEvent(SynchronizedEventSubscriber.java:47)
at com.google.common.eventbus.EventBus.dispatch(EventBus.java:322)
at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:304)
at com.google.common.eventbus.EventBus.post(EventBus.java:275)
at net.minecraftforge.fml.common.LoadController.sendEventToModContainer(LoadController.java:211)
at net.minecraftforge.fml.common.LoadController.propogateStateMessage(LoadController.java:189)
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.EventSubscriber.handleEvent(EventSubscriber.java:74)
at com.google.common.eventbus.SynchronizedEventSubscriber.handleEvent(SynchronizedEventSubscriber.java:47)
at com.google.common.eventbus.EventBus.dispatch(EventBus.java:322)
at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:304)
at com.google.common.eventbus.EventBus.post(EventBus.java:275)
at net.minecraftforge.fml.common.LoadController.redirect$onPost$0(LoadController.java:53)
at net.minecraftforge.fml.common.LoadController.distributeStateMessage(LoadController.java:118)
at net.minecraftforge.fml.common.Loader.serverStarted(Loader.java:800)
... 3 more

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

-- System Details --
Details:
Minecraft Version: 1.8.9
Operating System: Windows 10 (amd64) version 10.0
Java Version: 1.8.0_92, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 236332008 bytes (225 MB) / 995622912 bytes (949 MB) up to 1908932608 bytes (1820 MB)
JVM Flags: 1 total; -Xmx2G
IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
FML: MCP 9.19 Powered by Forge 11.15.1.1902 5 mods loaded, 5 mods active
States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored
UCHIJAAAA mcp{9.19} Minecraft Coder Pack
UCHIJAAAA FML{8.0.99.99} Forge Mod Loader
UCHIJAAAA Forge{11.15.1.1902} Minecraft Forge
UCHIJAAAE sponge{1.8.9-1890-4.2.0-BETA-1547} SpongeForge
UCHIJAAAA ninja.leaping.permissionsex{2.0-SNAPSHOT} PermissionsEx
Loaded coremods (and transformers):
SpongeCoremod (spongeforge-1.8.9-1890-4.2.0-BETA-1547.jar)
org.spongepowered.common.launch.transformer.SpongeSuperclassTransformer
Profiler Position: N/A (disabled)
Player Count: 0 / 20; []
Is Modded: Definitely; Server brand changed to 'fml,forge,sponge'
Type: Dedicated Server (map_server.txt)

As shown in the topic for PEX, the latest versions are only for API 5 (MC 1.9+). You should be using a build 131 or earlier on a 1.8.9 server.