I did some more digging and found this quote from ice trey, which even breaks down to what mechs should not belong to the Draconis Combine..
So perhaps if some mechs receive a bonus, others would incur a penalty.
I do like the suggestion of reinstating repair and rearm for non-faction flavored mechs.
I would like to offer a revision to the "Mechs List" in the opening post, if I may.
First, the Dragon and Jenner are well known to be Draconis Combine favorites. The Jenner, however, is not a Combine-exclusive design quite as much as the Dragon, and tends to pop up in other factions, as well. There is no Jenner factory, as it got blown up during the Succession wars. However, there were enough of them produced to still be quite commonplace.
Reference:
Battletech 35121 - Technical Readout 3039, Page 112
The Quickdraw is another Kurita Heavy. Both the Draconis Combine and Free Worlds League produce it. For the DC, it's produced on Luthien by L.A.W., alongside the Dragon and Charger 1A1.
Reference:
Fasa # 1620 - House Kurita, The Draconis Combine. Page 138
The Atlas, Victor, Marauder, and Jagermech are produced on Quentin by Independence Weaponry. (Fasa # 1623 - Handbook House Davion, page 152) During the War of 3039 in July, it was taken by the 40th Dieron regulars, and has remained in Kuritan hands ever since. It has been instrumental in replenishing lost war material afterwards. By the time of the clan invasion, the Jagermech, Atlas, Marauder, and Victor were considerably more common in the hands of the Combine.
Reference:
Battletech #35014: Historical - War of 3039, Page 122, 132
The Draconis Combine, thanks to future Coordinator Theodore Kurita, also was able to broker a deal with Comstar that would recognize the autonomy of the Free Rasalhague Republic in exchange for significant military equipment, including Star League era mechs. This influx of equipment was used to outfit the newly created Ghost Regiments. (Applies to multiple mechs, but in this case, the Kintaro, Highlander, and King Crab apply)
Reference:
Battletech #35014: Historical - War of 3039, Page 21, 148
The Awesome can be readily found in any house military (Battletech 35121 - Technical Readout 3039, Page 154), and the Draconis Combine is known for manufacturing excellent PPC and Missile technologies, namely it's Lord Light PPCs. While the Awesome isn't manufactured with Lords Light PPCs, the Combine would be at an advantage to have Awesomes. The Random Assignment Tables in Historical War of 3039 show a comparatively large proportion of Awesomes in their Assault mech rosters, primarily the 8Q, but the 8T also appears.
Reference:
Battletech #35014: Historical - War of 3039, Page 150
Battletech 35121 - Technical Readout 3039, Page 154
The following quote can be found in the Technical Readout entry for the Hunchback:
"The design is particularly favored by the Draconis Combine
and Capellan Confederation as it fi ts the preferred dueling
nature and all-or-nothing tactics used by these states."
It appears quite frequently in the combines' medium mech roster. Historical 3039 shows the 4G, 4J, and 4P as readily available.
Reference:
Battletech #35014: Historical - War of 3039, Page 150
Battletech 35121 - Technical Readout 3039, Page 136
The Battlemaster is also a mech that is common among most inner sphere (And even in second-line clan) factions. Again, it appears quite prominently in Draconis Combine tables in Historical 3039 as the 1G configuration, but the upgraded 3S also appears in the tables for Era Report 3052, likely reflecting mechs that have received an upgrade kit.
References:
Battletech #35014: Historical - War of 3039, Page 150
Battletech #35220: Era Report 3052, Page 152
On the TRO page for the Griffin, you can read this excerpt in the deployment section:
"Any major military will have Griffins on their roster.
The Capellan Confederation is the only great House not
manufacturing the design, but they are able to purchase a
limited number from the Taurian Concordat."
It is prominent in the Historical 3039 and Era Report 3052 RATs, as well.
References:
Battletech #35014: Historical - War of 3039, Page 150
Battletech #35220: Era Report 3052, Page 152
Battletech 35121 - Technical Readout 3039, Page 287
On the TRO page for the Shadow Hawk, it's stated that the Shadow Hawk is available just about everywhere, and even seems to put special emphasis on the 2K variant used by House Kurita's Second Proserpina Hussars.
It is prominent in the Historical 3039 RATs, as well.
References:
Battletech #35014: Historical - War of 3039, Page 150
Battletech 35121 - Technical Readout 3039, Page 289
On the TRO page for the Wolverine, you can read this excerpt in the deployment section:
"The Federated Suns’ capture of the Capellan’s Nanking
Wolverine line during the Fourth Succession War was off set
by the loss of their own Wolverine line on Marduk to the
Draconis Combine."
It is prominent in the Historical 3039 and Era Report 3052 RATs, as well. Namely the 6R, 6K, and 7K.
References:
Battletech #35014: Historical - War of 3039, Page 150
Battletech #35220: Era Report 3052, Page 152
Battletech 35121 - Technical Readout 3039, Page 290
The Locust also seems to play a large role in the Draconis Combine military, Cheap and plentiful, the 1V is the most popular, but the 3M, 3V, and 1E also appear to be in the roster.
References:
Battletech #35014: Historical - War of 3039, Page 150
Battletech #35220: Era Report 3052, Page 152
Battletech 35121 - Technical Readout 3039, Page 281
Another mech that is often listed as a mech available to most everyone, the Orion, appears to play a very large role in the armies of the Draconis Combine prior to the clan invasion. RATs seem to hint (and I conject) that many were lost during the invasion, and were likely replaced with newly built Jagermech, Marauder, Grand Dragon, Mauler, Charger 1A9, and Hatamoto mechs.
References:
Battletech #35014: Historical - War of 3039, Page 150
Battletech #35220: Era Report 3052, Page 152
Battletech 35121 - Technical Readout 3039, Page 152
While most often seen with the Capellan Confederation, the long out of production and increasingly rare Catapult is somewhat more common than normal in the Draconis Combine, as well.
"The Draconis Combine also obtained a sizable
group when they seized Dieron."
RATs for the era in Historical 3039 show only K2 variants, however, likely meaning that the majority have been converted to carry Kurita-made PPCs.
References:
Battletech 35121 - Technical Readout 3039, Page 146
Battletech #35014: Historical - War of 3039, Page 150
The Stalker is also listed as the most common assault mech in the Inner Sphere. It is no exception in Draconis Combine space, making up a significant proportion of the pre-invasion Battlemech roster in the Inner Sphere. 3F is the most popular, but the 3H and 4N also appear.
References:
Battletech 35121 - Technical Readout 3039, Page 162
Battletech #35014: Historical - War of 3039, Page 150
The Upcoming Panther is a mech that is extremely linked to the Draconis Combine, arguably even more so than the Dragon. The Grasshopper is readily available in every faction, somewhat significant in the combine's tables, making it an excellent flashbulb mech for the Combine roster.
References:
Battletech #35014: Historical - War of 3039, Page 150
Battletech #35220: Era Report 3052, Page 152
Battletech 35121 - Technical Readout 3039, 114, 151,
The Banshee 3E, Trebuchet, Firestarter, Raven, Thunderbolt, and Cicada are also available, but aren't hugely prominent in the Draconis Combine roster. They can believably be included, but don't play a huge part.
Reference:
Battletech #35014: Historical - War of 3039, Page 150
Battletech #35220: Era Report 3052, Page 152
Thanks to IDG for pointing it out, but the raven was also sold in small numbers to the Combine in order to boost Capellan coffers.
Reference:
Technical Readout: 3050 Upgrade[color=#959595], p. 30.[/color]
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Alright... how about mechs that are UNLIKELY to be found in the Draconis Combine?
Raven - A tightly guarded Capellan (Liao) secret only just starting manufacture near the 4th succession war. Many became captured by the Federated Suns.
Cataphract - A tightly guarded Capellan (Liao) secret only just starting manufacture near the 4th succession war. Many became captured by the Federated Suns.
Vindicator - a Capellan staple design, but like the Draconis Combine Panther and Dragon, aren't usually seen outside of that faction.
Commando - While it was common in the Draconis Combine during the age of the Star League due to mechs still being relatively new and limited in number (The ubiquitous Jenner and Panther would not be created until close to the fall of the Star League. See production dates shown on the Introductory boxed sets), and it could be captured during raids and taken as battlefield salvage, it hasn't been commonly used by the Combine in an age. The only instance I have found it represented in the Draconis Combine RATs is an RAT shared with the Free Rasalhague Republic - which sports both Kuritan and Steiner mechs. It's safe to recognize that the Commando is a workhorse Lyran (Steiner) light, and doesn't often show up in any other house army.
Blackjack and Centurion - These are both primarily Davion mechs. The few in Kuritan space would be battlefield salvage only.
The upcoming Enforcer is a mech found almost exclusively in Davion space, and is considered one of their trademark designs
The upcoming Zeus is a mech found almost exclusively in Steiner space, and is considered one of their trademark designs
TL;DR:
Definitely Available:
Dragon
Jenner
Spider
Victor
Atlas
Jagermech
King Crab
Highlander
Kintaro
Quickdraw
Hunchback
Orion
Griffin
Shadowhawk
Wolverine
Locust
Awesome
Battlemaster
Catapult
Stalker
Panther
Grasshopper
Could be included
Banshee (3E only)
Trebuchet
Cicada
Thunderbolt
Firestarter
R1