You may want to Google "USMC YEAR LOCATION" for definitive pictures.
I spent 2006 in Multi Nation Division Baghdad operating with 4th ID and 1st Cav on loan from the Navy to the 354th Civil Affairs Brigade. This is what I saw in Iraq and Kuwait
Early to mid War, Marines wore DCU (not chocolate chips), with BDU vests, DCU helmet covers, and tan boots.
Sailors loaned to Civil Affairs wore DCUs with DCU vests, DCU helmet covers, tan boots, and Army unit/combat patches. Both Marine and Navy were issued green knee / elbow pads and green Kevlar gloves. Packs and web gear came in OD, BDU, DCU, and ACU. (I replaced everything I was issued in OD / BDU / ACU from surplus stores around Fort Bragg). My unit had a bit of a mutiny at the IBA depot when they refused to issue DCU vest covers to Sailors a gaggle of Senior Naval Officers executed a 1960s still sit-in until they rustled up the DCU covers. Similarly, we also demanded DCU helmet covers. They finally hailed out a triwall of used covers including some with bullet holes and even blood.
Traditional Navy units (Seabees, Cargo battalion, Fuel, Medical etc). Wore full DCU uniforms and kit, but not patches.
Army started in DCUs and transitioned to ACU in 2005. This resulted in some loaned out Sailors wearing ACU and even combos of ACU / DCU / BDU. SF and Delta folks I worked with wore standard army gear. Not sure about folks in the A-Teams.
Air Force wore DCUs similar to Navy.
Due to increased vehicle crew losses in 2006, that fall they issued Tan flame resistant coveralls in MNDB (not sure about elsewhere). These were to be worn with flash gear for head and hands under helmets, vests, and web gear. We received directives to leave our black pile jackets, black high-speed longjohns, and other stuff that would melt in the Hooch when we went outside the wire. Here is a link to some female marines in these. link
I also saw a lot of vehicles with mismatched cammo. Lots of BDU stuff replacing or strapped onto mostly tan tactical vehicles. OBTW, inside the wire most units also had nontactical vehicles such as Broncos, Blazers, Suburban, and SUVs generally painted white, grey, and black wuth a few in yellow, red, and blue.
Iraqi army wore Chocolate chips with boots or sandals and the Police had Blue Tactical uniforms. Our Iraqi embeds wore Chocolate chips if interpreters and Bilingual Bicultural Assistansts (BBAs) plus US civilians such State Department and consultants wore civil clothes with OD or BDU vests with plain green Kevlar helmets (no covers).
The mercenaries such as Blackwater wore a mishmash of civilian clothes and camouflage tactical gear. Triple Canopy and other uniformed contracted Civilians wore various camouflage uniforms and tactical gear. The fellows from Uganda were very squared away in their crisp uniforms, well cared for kit, and crisp accents.
The enemy was wearing just civilian clothes by mid-war and blended into the populace with an AK being their identifying piece of gear.
What I described was 2004 to 2007. Not sure about transition dates after that. Here is a link to pictures of me and our unit flic.kr/s/aHsiPfCtPr plus one of a typical view out the window of my Humvee flic.kr/s/aHsiPfA6nJ