Joint Aggressor squadron???
Wouldn't it make more sense for the US to pool its Aggressor Squadrons? Which, could be supported by all three services. (i.e. USN, USMC, and USAF)
If you're still awaiting and answer after many moons...
Dissimiliar Air Combat Training (DACT) proved itself after it was formalized during the late sixties in the US Navy following the creation of the Navy Fighter Weapons School (TOPGUN). TOPGUN used borrowed aircraft such as the A-4 Skyhawk and even worked with the USAF reserve F-106 squadrons to provide Dissimilar presentations that mimicked the MiG-17 and MiG-21 being encountered over North Vietnam. The success of the Navy Phantoms afterwards, particularly in 1972, resulted in establishment of dedicated squadrons called Aggressors in USAF implementation and Adversary squadrons in the Navy and Marine Corps.
The Air Force created the first Aggressor unit at Nellis and equipped it with T-38 Talons (simulating the MiG-21) initially and then introduced the F-5E Tiger. Eventually, this manifested itself as 2 squadrons at Nellis and one At Alconbury in the UK and another at Clark in the Philippines. Meanwhile, the Navy transformed their existing Instrument RAGs (at Miramar, Oceana, Key West and Lemoore) that were equipped with TA-4J Skyhawks that were useful surrogates for the MiG-17 and later added the F-5E as well. The Marines later created an Adversary squadron at Yuma with the F-21 Kfir which was also operated by VF-43 at Oceana.
Although each service conducted DACT, they also established their own approach and syllabus. The Aggressor model provided a roadshow that visited units and the two units at Nellis also participated in Red Flag exercises. Navy fighter aircrews were exposed to DACT training during their initial FRS training syllabus at either Miramar or Oceana and developed a DACT intensive turnaround training syllabus called Fleet Fighter ACM Readiness Program (FFARP) conducted at Miramar and Oceana for the fleet fighter squadrons. Air Wing training at Fallon also used Adversary support for the entire air wing. FFARP preceded the Air Wing training at Fallon.The Marines used their Adversaries in support of their biannual WTI exercises at Yuma and supported individual squadrons upon request.
The highpoint of DACT was in the late 80s when the F-16 was introduced as both an Aggressor and Adversary asset in the USAF and USN DACT units. Then the Cold War ended and the peace dividend came due inthe aftermath of Desert Storm and specialized DACT units were looked upon as exspensive luxuries. By the mid nineties, the Air Force stood down
all their Aggressor units. Critics at ACC who had been huimbled by the Aggressors when squadron COs are rumored to have had a hand in suppressing the sometimes renegade Aggressors. A handful of F-16s remained at Nellis under another name to provide DACT support to Red Flag. The Navy disestablished
all 4 of its active duty Adversary squadrons at its Master Jet Bases and 6 of the VC squadrons leaving only 2 reserve VFC squadrons and the NSAWC Adversary assets to handle the requests for DACT. The Marines have maintained their Advesary unit which is now equipped with the F-5E.
Recently, the Air Force has brought back their Aggressor squadrons with both the F-16 and now the F-15 for the first time. They also used the West German MiG-29s on a regular basis since 1990 before they were stood down and transferred to Poland in 2004. The Navy recently reintroduced the F-16 to the Adversary role at Fallon (TOPGUN's unique F-16Ns were shut down earlier when they were found to have cracks from intensive DACT utilization) and has acquired former Swiss F-5Es and stood up an additonal reserve Adversary squadron at Key West to augment the dedicated reserve Adversary squadrons at Fallon and Oceana. The Reserve air wing also supports the DACT needs of the Navy with its F/A-18 squadrons and additional F/A-18s are flown by NSAWC in a DACT role.
So, to answer your question, the service approaches to maintaining readiness do not support a joint unit. DACT assets are currently located where they can support the operational units during their workups for deployment. Establishing a Joint unit for be optimum for one service and suboptimze the needs of the other services. The Navy and Marines have found use of experienced reserve pilots to be best suited to the Adversary role. One important aspect of DACT is the pilots. Use of an appropriate aircraft is critical, but so is a dedicated cadre of pilots who don't give into temptation to use their skills to win at all costs. Instead, they teach and emulate the appropriate tactics avoiding the pitfall that the USAF Aggressors fell into before they were virtually shut down.