There are a LOT of these. I haven't got a complete list (maybe later) but I have mecha listings right now for a few of them, courtesy of the old-version site on MS Lexicon.
These are all Tsukuda Hobby games, and should go under that section where Twilight of Zeon is.
Whenever there's time to organize the mecha listing index, I suggest that manga and novels should be separated out into their own subcategories. Perhaps distinguishing proper novels from model magazine articles and photo-stories, as well.
- MS-06FZII - Zaku II Final Production Type
- MS-06T - Zaku Training Type
- RX-78M - Gundam (Magnetic Coating)
That last one actually just says "Gundam (Magnetic Coating)" in katakana, and nothing else. I'm not sure exactly what to call it... especially if it's just this game's way of differentiating Amuro's Gundam pre- and post-magnetic coating. Without the game book, I guess we should just leave it at that.Cross of Zeon
MS Lexicon has a page for this, and a listing that's completely blank. Just the "newly introduced machines" heading, and none listed. I guess this means that there actually are no original mecha in this, since they bothered to make a blank page.Twilight of Zeon
- MS-06H - Zaku Minelaying Type.
(This uses different kanji from the original MSV books' F-type Minelayer Zaku; I don't know enough to clarify the difference.)
- MS-06L - Zaku Missile Equipment Type
- MS-06J - Zaku Reinforced Armor Type
(You could also go with "Strengthened", "Enhanced", etc. I believe we've seen this term before with its multiple translations.)
- MS-06G - Zaku High Mobility Type
(This is named with the same term used to describe the MS-06R series in MS Encyclopedia.)
- MS-14C - Gelgoog Cannon
(It says "MS-14K is described" in parentheses. Not sure what that signifies.)
- MS-15B - Gyan Mass Production Type
- MSN-02C - Zeong (Head)
- MSN-01 - Kikeroga
- RGM-79L - GM High Mobility Type
(Again, same kanji as the MS-06R. It says "RGM-79H is described" in parentheses; same as before.)
- RGM-79bis - GM Reinforced Armor Type
(Same deal as the Zaku.)
- RG-79AV - Gundam Mass Production Type
(RG? I guess that model number concept has fallen by the wayside.)