TerdyTheTerd

This is a just a guess based on other issues with macs I've seen. You might have a newer java version installed that Minecraft does not support. You will need to downgrade to version 8 or 9. I am not sure how to check on a mac so you will need to look that up before hand to make sure you don't have something like 11-13 installed.

There could be something that has one file open within the pack install location, a simple way to make sure everything is closed is to just restart the pc, which by the time you read this I would assume has happened.

I would say it could be possibly that the ram that has gone bad, but this is very unlikely if you are not experiencing other issues like BSOD. The only thing I know is that according to the logs Java is unable to allocate the specified amount of RAM. I do not know why that is happening. Have you tried reinstalling/updating Java yet?

What is up with the low effort post always having dark text? It's hard as hell to read. Change the text color and please provide us with a log from the launcher.

How much is free though? Are you running anything else like a server that might use up a good chunk of that? I would say normally users shouldn't have issues with not enough ram having 8gb, but then again I'm currently using 6bg and I only have chrome open (various background task are eating it up). Its possible you are already using too much and so the JVM cannot allocate the 2.5 that you told it to.

Just like any other mod, use the extract option of Optifines installer, then place that jar in the mods folder... (for my own sanity I just did it as described)

How much ram do you have? How much is already in use? It appears you are trying to allocate more than is available on the system.

and I take over for you when you aren't around

While Pixelmon support is not offered on these forums, its possible that mojangs servers were simply down at that time, have you tried again? Before messing with any host files or firewalls etc just try to ping "authserver.mojang.com" via command prompt or even just paste in that in the url to see if you can access it at all

You have Ice and Fire installed but you do not have LLib installed As is also noted in the logs

Only way to know is to try it out. Ram could be an issue as your usable amount will be somewhere around 2gb, might be able to squeeze 3gb if you limit everything running in the background. I am not familiar with that CPU, but a quick look at the benchmarks for it I would assume there is going to relatively low fps, likely around the 20-30fps area? Really hard to tell, also depends on the version, what settings you use and any performance mods you might add.

Try looking at the crash reports, I bet we can find some useful info in them. Upload one here using a pasting service

Based on the log I am assuming you are connecting to a server, in that case there's a high probability this is caused by different configs on the server <-> client. Make sure the client has the same configs, especially for id's, as the server is running.

You are using the latest forge, 2854, you must use the installer file not the universal. There are many similarly titled threads with the same problem/solution to look at on there forums, always make sure you take a look before posting

Occasionally java will get it's window "stuck" outside of the desktop screen for various reasons, this sounds like this might be the case. One possible solution is to shift+right click on the icon, click "move" then press any arrow key to bind to the window. You should now be able to move the cursor around and see the minecraft window come back into view. This has worked for other users, assuming this is indeed the same problem.

Please read any of the dozens of recent, similarly titled issues that all have the same resolution, or if you're lazy and can't be bothered, see below. When using the most recent forge version (2854) for 1.12.2 you have to follow the new installation method. That is, rename the installer file to modpack, not the universal.

Did you remove all the client side mods when moving it to the server?

Will need more details, what pack is this? Does this happen on other packs? How Much RAM are you allocating? There's not to go off of here... A log file would also be useful.

Based on other threads make sure LegacyJavaFixer is installed. However turning off the version checker should already solve this issue, odd that you claim it does not. Here, here and here

You can try deleting both the bspkrsCore and treecapcitor config files to let the regenerate (assuming there is one for each). I do not know what version this is, and I would assume they are already up to date, but double check and make sure they are both the most recent versions.

He is using 1.12.2, make sure you rename the installer file if you are using the most recent forge build 2854.

Do you have a log for us to look at?

Be patient, this pack takes a very long to install. Seems to be an issue with wherever the author is hosting the file. I have Gigabit internet but the pack was only installing at >1MB/s which is very slow.

Looks like you used the universal forge version, use the installer file renamed to modpack.jar if you are using the latest forge for 1.12.2.

If you are only seeing 1gb as an option then you have 32bit java installed, you need to install 64bit java and remove the 32bit. There are plenty of guides on installing java online, its very simple. On a side note Pixelmon support is not offered on these forums. Future issues that are Pixelmon related need to be made elsewhere.