The fanfics i ve read being a SRW Alpha 3 crossover. In that particular fanic, the author generally have the UC era gundams do good against the BETA until they run out of E-packs on their beam rifle, or when their head vulcans run out of ammo and they get swarmed by Tank classes. Seed CE era Phase-shift can survive the tanks quite well provided their batteries last. I-field are somewhat weak against lasers since BETA lasers are not Minovsky particle based beams. after colony wing series Gundams can survive the lasers class for a bit due to the insane heat resistance of the Gundanium alloy it helps that their pilots are all god tier experts in hit and run. Macross Valkyries do well in there Gerwalk mode since they all have unlimited flight time plus unrivaled 3 dimensional maneuverability in tight spaces allowing them to hover over the BETAs and dance all over the place. Evangelions are pretty godlike against the BETA clasees with their AT-fields but if exposed in the open where thousands of Magnus LUX lasers can target them, then their AT-fields will collapse just like when the evas fought Ramiel.
Orginal generation units like the R-series and other OG original units also do pretty good in close quarters due to all of them using tesla-drives and other various EOT Balmar, T-link technology that lets them maneuver without obeying the laws of momentum and conservation of energy.
Also "Real men ride each other"= BETA pwnage. Zankantou that cleaves evil and Trombe over ride, I ain't gona explain shit.
There is just so much shit in this fic its ridiculous. sadly its in Japanese, though someone did translated into Chinese as well.
The fic in question is called Muvluv: to the end of the galaxy.
It crosses muvluv unlimited+TDA with Post SRW Alpha3 Cobray route. The author try to use some"realisim", such as many of the weapons and attacks are not allowed to be used while within or around earth(you can guess which ones.) its post final mission true end in @3 after fighting off Keisar Ephes that when The alpha numbers attempted to jump back to their original time space with the power of Irui Gun-eden and Ideon that they got sent to the Muvluv unlimited TDA verse instead . So almost all units are damaged to some degree or outright unusable and running low on ammo after the Keisar ephes fight. Of course many of these repairs and resupply will be difficult or straight up impossible to acquire in muluv earth.
For the MLU side, its after the evacuation of the colony ships but before the global G-bombing phase of op Babylon. Takeru gets meiya's 00R repainted in black. the valkyries and 207 are around but disbanded and spread out all over the world. Marimo is back to being a major in the IJA and eventually gets her own battalion affiliated with the UN curiously named "Wardog" battalion which will get many members who we are familiar with from the various TDA and chronicle side stories. Also the Americans are scheming something huge with the the arrival of the alpha numbers. Cobray and Dis Astragant choose to TIME DIVE into extra before Time diving again into Alternative.
the following is the translated teaser i did using various quotes from the Fic for /m awhile ago. see if you can guess who is saying what.
Spoiler:
"All right gentlemen, Imperial Japan have given us permission to enter its airspace. The Ra Cailum will now enter condition red. Torres,disperse Minovsky particle at combat density and time the firing of our mega-particle cannons with the Archeangel's Lohengrin cannon. The eastern beach head of Sagoshima will be cleared before we deploy our Mobile suit teams. Amuro, Kamille, Burning, are your teams ready?"
"Shinji the BETAs are not allowed to breach the main gate on the No.2 runway. Assist the The A-01 the best you can."
"Got it, they will not harm the Xg-70 while Unit-01 and I still stand."
"ughhhh.. this is so retarded....why does baka shinji gets to sit on his lazy ass while we are litrerally knee deep in these disgusting BETA. these beta just keep coming out of that tunnel , just how many are there and wtf is that rumbling. Ayanami? are you listening to me Ayanami? Oh God! what are you doing with that N2 Mine?! Rei Are you fucking insane?! WE ARE IN A TUNNE-------------BOOOOOOOM" (later an offical UN investagation was ordered on the alpha # for what is believed to be an unsanctioned illegal use of an nuclear weapon within the vicinity human settlement,the alpha number representative Taiga Kohtaroh was quick to point out the difference between N2 and traditional nuclear weapons.)
"Mission acknowledged..... Target lock..... Magnus Lux swarm.....show me their fate Zero."
"Tomoro 0117 activate ES-window and raise J-jewel output to 30%. Those who wish to steal the joy of soaring freely in the skies are my enemy, anti-meson cannon prepare to fire."
"Not bad,not bad. you guys certainly live up to the name Valkyries. "
"What do you mean Lt.... Isamu Dyson was it? Is there a unit named Valkries as well where you are from ?"
"Not exactly. This baby i m using here is called a Valkyrie type fighter. Technically This one is a VF-19"Excalibur" and Valkyries are the first or VF-1, though somehow everybody where i m from ended up calling them all Valkyries....If you want Lt Mitsuki i m sure i can teach you to be a true Valkyrie pilot after we are done here"
"Isamu! we are in combat what are you doing chitchatting!"
"Jesus, Guld can't a man have a nice conversation with a pretty lady in peace."
"I'm telling Myung...."
"Why does that senju.. i mean gundam remind me of Meiya?"
"What the! who just launched !? i did not give any permission to launch yet."
"I'm sorry Captain, its Basara and Sivil... we couldn't stop them. He said he wanted to sing...."
"Are you telling me they have a 70KM warship parked over our heads.and that an even more insane and logic defying group of these people and their..machines.. are clearing the hives on Mars as we speak?"
"yes, they said they did something they called a route split."
also yuuko destroys her office in rage like 18 times from just even trying to understand the various bullshit workings and energy source of the various SRW units. The real type she could somewhat understand and rationalize their theory, but stuff like the Ide, Getter ray, J-jewel/G-stone, Tetragrammaton and other Super-Robot Not!Magictek science makes her want to blow her brains out.