E.F.F.:
RGM-79R/RMS-179 GM II (official site has the incorrect OYW GM upgrade designation wrong; GM IIs built after their introduction in the early 0080s use the RMS designation)
MSA-005K Guncannon Detector (Zeta Mobile Suit Variations, built on the Methuss frame during the Gryps conflict; some/all of these are newly built, as Anaheim Electronics originally built two for Karaba.. one of which was lost during in re-entry for delivery)
RAG-79 Aqua GM
MSA-003 Nemo (developed from the GM II, with design influences from the GM Sniper II and incorporating the Movable Frame technnology from the Gundam Mk. II in the early stages of the Gryps conflict)
RGM-96X Jesta (developed from the Jegan; as the official profile notes, their intended role is to suppress normal forces, to allow the two NT-D equipped Gundams to focus on enemy Newtypes)
RGM-96X Jesta Cannon (if not in Ep.4, then Ep.5)
Only 12 Jestas produced; assigned to the Ra Cailum for evaluation.
RMV-1 Guntank II
RMS-179/RGM-79R GM II variation with the Ground Gundam/GM's shield (brand new for Unicorn)
RX-160 Byalant
RX-0 Unicorn Gundam "Banshee" (at the Augusta Newtype Labs)
AMX-004G/AMX-017 Qubeley Mass Production-type (surviving unit present at Augusta)
Neo-Zeon/Earth-based Zeon Remnants:
AMA-X7 Shamblo
AMS-129M Zee Zulu
MS-05L Zaku I Sniper
MS-06D Desert Zaku (improved version of the original Zaku Desert Type from the OYW; improvements to mobility, power output, and thruster fuel capacity compliment the sand filters that allow it to be buried for ambushes in the desert)
MS-06K Zaku Cannon
RMS-192M Zaku Mariner
AMX-101K Galluss-K (uses the Hyper Knuckle Buster beam cannon of the AMX-008 Ga-Zowmn, from which it was canniballized primarily due to the relatively poor maintenance capability of the Earth-based Zeon Remnants and lack of parts for the maintenance-intensive transforming MS of previous wars)
RMS-108 Marasai (somewhat surprising it shows up in Unicorn, considering it was never produced in overly large numbers despite its marked superiority to the Hi-Zack; the few Titans that survived the Gryps conflict were largely used as fodder by the Haman and Glemly factions in ZZ)
MSM-07 Z'gok (OYW survivor; as the official profile notes, it's still deadly nearly two decades after introduction, pretty much due to very little advancement in amphibious MS. Interesting side-note: MSV-sources suggest that these Z'gok are likely of the S-type, or the "later production type" bloc.)
MS-09F/trop Dom Tropen
MS-09G Dowdage
MS-06V Zaku Tank
MS-07C-3 Gouf Heavy Arms-type (dual hand machine cannons)
AMX-109 Capule
MSM-04G Juagg (with beam cannons)
MSM-08 Zogok (land combat variant; brand new variation)
MS-08TX/N Efreet Nacht (kunai-armed)
MS-14D Gelgoog Desert-type
Many Zeon MS from 0080: War in the Pocket
Unconfirmed appearances:
MSA-004K Nemo III
AMX-101 Galuss J
Ships:
Federation:
Ra-Cailum and Clop-classes (pretty much unchanged from CCA).
A Pegasus-class refit similar to the Albion from 0083, or the Thoroughbred/Grey Phantom refits of 0080. It seems it -may- be the Albion, but I can't confirm yet.
Zeon:
Mad Angler-class (has recieved some refitting, since the OYW).
Jukon-class refit submarine (not the original type; see U-801 from 0083); it is the same Jukon-U Himalaya from the novels.
Expect more MS to show up in Ep.5 as the Republic of Zeon enters the conflict..
Republic of Zeon:
RMS-106 Hizack (RoZ colors; we'll likely see some of the second-line Federation units still using these, in their dark navy blue Federation colors)
RMS-106CS Hizack Custom (RoZ colors; also probably with alternate armaments..)
RMS-119 EWAC Zack "Eye-Zack" (RoZ colors)
RMS-099B Sturm Dias
RMS-117B Galbaldy Beta
MS-11 Act Zaku (might show up in Ep.4 with some of the Earth-based Zeon Remnants too)
MS-09R Rick-Dom (some might be using the rocket bazooka the Dreissen uses)
Ships:
Probably the usual mix of Musais (of all production blocs, but mainly the Musai Kai), Chivvay Kai (probably some of the earlier models too), and some other castoffs from Zeon remnants that didn't join Haman/Char/Full Frontal.
Some hint dropping in Gundam-centric publications and such also suggest we'll be seeing some relative rarities as well (variations, etc.).
Also, expect the following in Sleeves markings:
RMS-154 Barzam
NRX-044 Asshimar
AMX-011 Zaku III
AMX-014 Dooben-Wolf
AMX-102 Zssa
AMX-008 Ga-Zowmn
AMX-107 Bawoo (production model; lacks the second cockpit in the lower body-half).
On the Federation side:
RGC-90 Jegan Cannon
RAS-96 Anksha (GM-ized Asshimar)
Also seems like the mass-production MS from Sentinel will make cameos; examples being the Nero, Refined Barzam, and Xeku Eins. I suspect this is probably speculation, unfortunately.
Finally, Episode 5 will probably mark the introduction of the Dogosse Gier-class battlecruiser, General Revil, as well as old vessels like the Salamis Kai-class cruisers , and Columbus Kai-class carriers.