Kinda lol that you can even drag Megaman into area of Gundam...
Meh...I'll give some of my opinions:
BD1 or BD2 can probably present Rock/X better, as of course they're blue, good in any range of combat, EXAM system can kinda be seen as when they're bursting their "potential energy" out (ever played Maverick Hunter X? Seeing X's red jewel on his head glow?)
When you said Protoman, the first thing I think of is Gelgoog, simply because they have a very similar shield, also good at all range of combat (classic Protoman is good at shooting, EXE Protoman is good at meleeing)
If there is Exia Repair II, it can definitely represent Zero...(green blade, little amount of range weaponry), but since there's not one, I think Nadleeh probably suits, good with melee, and most importantly, got long hair too XD
Agreed with Colonel and Iris, but too bad Crossbone don't have a cape...
As for the rest, I don't see anything but that you choose Forte for Heavyarms, there's like tons of Megaman Boss that got heavy weaponry like Heavyarms (Napalm Man from MM5, Commando Man from MM10, etc.)
...oops, I got serious.