Trying to play on a Pixelmon server. Have to go to 1.7.9 or it will tell me that I was kicked because of being in an "Outdated Server! I'm still on {0}."

Please attach the crash report ([minecraft|http://hopper.minecraft.net/help/finding-minecraft-data-folder]/crash-reports/crash-<DATE>-client.txt), otherwise we can not diagnose this issue.
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Minecraft Crash Report ----
// Don't do that.

Time: 7/13/16 9:56 PM
Description: Ticking screen

java.lang.IndexOutOfBoundsException
at java.nio.Buffer.checkIndex(Buffer.java:540)
at java.nio.DirectIntBufferU.get(DirectIntBufferU.java:253)
at bom.a(SourceFile:271)
at bom.a(SourceFile:220)
at ban.a(SourceFile:1694)
at ban.a(SourceFile:1652)
at bln.a(SourceFile:123)
at hd.a(SourceFile:70)
at hd.a(SourceFile:13)
at ej.a(SourceFile:174)
at bct.c(SourceFile:78)
at ban.p(SourceFile:1343)
at ban.ak(SourceFile:774)
at ban.f(SourceFile:728)
at net.minecraft.client.main.Main.main(SourceFile:148)

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

– Head –
Stacktrace:
at java.nio.Buffer.checkIndex(Buffer.java:540)
at java.nio.DirectIntBufferU.get(DirectIntBufferU.java:253)
at bom.a(SourceFile:271)
at bom.a(SourceFile:220)
at ban.a(SourceFile:1694)
at ban.a(SourceFile:1652)
at bln.a(SourceFile:123)
at hd.a(SourceFile:70)
at hd.a(SourceFile:13)
at ej.a(SourceFile:174)
at bct.c(SourceFile:78)

– Affected screen –
Details:
Screen name: bct

– Affected level –
Details:
Level name: MpServer
All players: 0 total; []
Chunk stats: MultiplayerChunkCache: 0, 0
Level seed: 0
Level generator: ID 01 - flat, ver 0. Features enabled: false
Level generator options:
Level spawn location: World: (8,64,8), Chunk: (at 8,4,8 in 0,0; contains blocks 0,0,0 to 15,255,15), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Level time: 0 game time, 0 day time
Level dimension: 0
Level storage version: 0x00000 - Unknown?
Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
Forced entities: 0 total; []
Retry entities: 0 total; []
Server brand: ~_ERROR~ NullPointerException: null
Server type: Non-integrated multiplayer server
Stacktrace:
at blr.a(SourceFile:289)
at ban.b(SourceFile:1972)
at ban.f(SourceFile:737)
at net.minecraft.client.main.Main.main(SourceFile:148)

– System Details –
Details:
Minecraft Version: 1.7.9
Operating System: Windows 10 (amd64) version 10.0
Java Version: 1.8.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 117916664 bytes (112 MB) / 181555200 bytes (173 MB) up to 1060372480 bytes (1011 MB)
JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Launched Version: 1.7.9
LWJGL: 2.9.1
OpenGL: Intel(R) HD Graphics 4600 GL version 4.3.0 - Build 20.19.15.4331, Intel
GL Caps: Using GL 1.3 multitexturing.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Anisotropic filtering is supported and maximum anisotropy is 16.
Shaders are available because OpenGL 2.1 is supported.

Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Packs: []
Current Language: English (US)
Profiler Position: N/A (disabled)
Vec3 Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
Anisotropic Filtering: Off (1)

That is what I get when I run 1.7.9.

1. Dupe of MC-38527. See that ticket for instructions on how to fix your issue.

2. Please note your version of Minecraft is outdated. Only submit bugs found from the latest version, 1.10.2.

3. The server you are trying to play is most likely modified. (Although your game may not be modified, the server can be) Only submit bugs from the vanilla version of the game.