GBRs, Guppies, Rainbow Fish, and Red parrots?
 

My friend is moving and he is going to give me a 150 gallon
tank and I was thinking about making it a heavily planted
community tank. Would all of these fish be compatible?
German Blue rams, Red parrots, Rainbow fish, and guppies?
I could take out the guppies though.
My stocking plan would be:
-4 Red parrots
-4-8 rainbow fish
-4 GBRs
- 4-10 guppies
-4-10 neon tetras?

You have a mix of fish with different and conflicting needs and to top it off some will grow big enough to eat others. I'd pick a fish I really love and then browse the care-sheets on seriously fish or another reputable site to find compatible tank mates. A carefully crafted stock list will give you a more attractive tank and far less trouble in the long term.

Blood parrots are a bit controversial, if you want some you should probably look into their origins and health problems before you buy.

Oh I forgot to list this detail. I already have
GBRs and Blood Parrots in another aquarium
atm. The BPs have been there for 4-6 years, and
the GBRs just a couple days ago. I have some
guppies I want to put in from my 55 gallon.
The only "new" fish I'm getting are the rainbows
and probably some tetras.

You put GBR in with blood parrots? Interesting

Yup. My first try was adding the GBRs in while
the Parrots were "established" in the tank already,
the BPs chased them around. Then, I removed
the BPs and let the GBRs stay in there for 1 hour
and 30mins and added the BPs. It went well. :)

Are your rams colored up or are they pale? Do you have a lot of cover for them? I would think that's a very stressful situation for them to be in.

They are in a heavily planted 75 aquarium, tons of cover.
My male looks to be pretty colorful ever since I started
feeding blackworms. My female stays near the moss and
looks the same. I've noticed the BPs stay on the right of
the tank and the GBRs go on the left.

Ok cool! I was starting to feel
Bad for the lil guy's. lol!

GBR's really need higher temps and lower pH than most community fish.. I wouldn't have the parrot fish with guppies and tetras? I don't think.. The Rams should be fine with guppies and tetras if the temp and pH match up. But I'd be inclined to think the parrots would end up bullying, harassing, damaging and eventually killing the smaller fish.
Rainbows would also cope with (depending on the species) higher temp and acidic pH. But again, they're not aggressive fish (aside from displaying their colors to one another) and I wouldn't put them with blood parrots.

I know you want to move the parrots over from another tank, but the list without those in a community tank kept at a higher temperature tank would be lovely.

Just my input, of course.

Ditto Ony's post:
Fish may eat each other.
Fish have different needs.

I would separate your fish list into each of the tanks you have and better accommodate each species' physical needs (temperature, water movement, water chemistry) and social needs (similar sized fish, claim territory in different parts of the tank, not afraid of tank mates).

Ok, I'll have to give away or sell my BPs then.

My stocking plan would be:
4 Red parrots - get rid of it.
4-8 rainbow fish keep this group at 8
4 GBRs - add 4 more
4-10 guppies - get rid of it
4-10 neon tetras - up the # to 20+

your list is fine, neon are big enough, not small enough to fit the mouth of the ram or rainbow.
I would do 1 male to 2 female for the ram and rainbow.

That's a good stock list, but
I think I'm going to need more
fish. 150 gallon tank we talking
here. XD