A comparison or fight between Raigo and the F91 has to many variables to actually be a good example really. While F91 has it's piercing beams and it's after images most of Raigo's packs have versatility to allow the pilot to distract and push hard on a suit. Or straight out overpowering a suit in the case of a sumbullet pack if it get's a less than agile enemy. However pack changing takes a bit of time so Raigo would be open during the pack change unless it managed to get a pause in the fight to do so it wouldn't end well. And the flight pack isn't as big an advantage as you say it is in the video of it by gundam info it clearly shows the F91's abilities in air to air combat as being at least passable enough to take on enemy units in brief gun to gun fights.

[youtube]WpcIf0Dbin8[/youtube]

The specs for Gundam X and RX-78 are the following:
Model number: GX-9900
Code name: Gundam X
First deployment: pre-A.W. 0001 
Accommodation: pilot only, in standard cockpit in torso
Dimensions: head height 17.1 meters
Weight: empty 7.5 metric metric tons; max gross weight unknown
Armor materials: lunar titanium alloy armor and frame
Powerplant: ultracompact fusion reactor, power output rating unknown
Propulsion: unknown 
 RX-78
Accommodation: pilot only, in standard cockpit in torso with Core Block System using FF-X7 Core Fighter
Dimensions: overall height 18.5 meters; head height 18.0 meters
Weight: empty 43.4 metric tons; max gross 60.0 metric tons
Armor materials: lunar titanium alloy 
Powerplant: Minovsky type ultracompact fusion reactor, output rated at 1380 kW
Propulsion: rocket thrusters: 2 x 24000 kg, 4 x 1870 kg
Performance: maximum thruster acceleration 0.93 G; 180-degree turn time 1.5 seconds (1.1 seconds after magnetic coating upgrade); maximum ground running speed 165 km/h

In terms of weight and height it goes to the RX-78. In terms of speed it goes to the Gundam X. Weapons being special on one end is a bazooka and a gundam hammer for the RX-78. The Gundam X has it's satellite cannon, the shield buster rifle, and the Flash system. On a one on one fight the chances of charging up for a satelliate cannon shot is pretty poor and the machine wouldn't be able to use bits if it did it would be over for most suits. I'd give this match up to Gundam X for a speed edge and it's shield buster rifle. The machine is no joke but if I could compare it to the F91 I'd think it comes up lacking due to the machine's beam weapons, and it's after images. It is likely being a mass produced gundam does it no favors as well.If you compare it to the wing suits like you say it comes down to the ability of X to dodge wing's buster rifle, not lose sight of deathscythe, overwhelm sandrock, and out melee/shoot Shenlong while avoiding being lit on fire or smacked with the dragon head. Heavyarms is out of luck in a one on one fight likely due to it's primary weapon being a Gatling gun and missiles which may prove less than effective against the buster shield rifle and the vulcans of X. 

Not to discredit heavyarms but it's uses are limited to overwhelming with firepower and with the gundarium alloy used by x it'd be tougher than usual to fight off in close combat. It (gundam x) comes out on top only if it can do those things but it only takes one hit to kill X by way of Shenlong, deathscythe, and wing gundam. I'd call it a win for shenlong, wing, or deathscythe. Sandrock could very well beat Gundam X if sandrock managed to cleave through it's shield and keep itself from being fired upon too much. Heavyarms may be able to win if it's weapons can pierce the gundarium armor of X. 

 Gundam X fighting F91 leaves it with only the options of a Satellite Cannon shot or beam spamming with it's rifle. It could last for a bit against f91 but in the end it goes down with the power of piercing beam weapons eventually getting through the buster rifle shield or outmaneuvering it from above.

Sandrock vs. F91 is simple going by the video above it seems all it needs to do is keep in the air and unless Sandrock can throw those shotels pretty well it's going to have a hard time winning. It's very possible to end in a draw due to the study nature of Sandrock but it is what it is.

The machines do in fact have infinite power without Trans-Am activated and once they activate it they either win or they lose massively in performance. They've been fought off by grunt units in mass before and Graham/Ali have shown repeatedly that they can be beaten or outmatched into a draw. The ability to move the way they do is because of the machines' pilots. Lockon, Ali Al Sanchez, Innovades, Setsuna, and Allelujah are all masterful pilots due to either a high talent for piloting that exceeds most pilots, genetical enhancements, or superior technology. Graham was able to fight on par with setsuna using the flag, Allelujah is a super soldier literally, and all of the suits were pretty high tech. If you put Lasse in Exia and throw him against Graham I'd believe Graham could beat Lasse instead of the massing draws between him and Setsuna. Setsuna's ability to move Exia is due to how well it's made and how well he knows how to pilot the thing. A mobile trace gundam fighter has instantaneous reactions to everything the pilot does physically. If you put Lasse in Exia with a gundam trace system he may very well be able to move on Setsuna's level and keep up with Graham. The key to F91 beating Exia is using the after images. Otherwise if it tried to straight up fight Exia it may go very bad for it. I'd give Exia the win but only due to how advanced Exia is in the hands of a skilled pilot. If you put Reve up against Leo there's a good chance Leo could beat Reve due to her overconfidence. But even then Exia is a powerful suit and it was made very well by Celestial Being. 

While after writing the above I may have accepted the fact that I may have hyped up the abilities of F91 with a old type pilot in it I still believe it is a force to be reckoned with. There is still a chance for the biocomputer to play a role in it even if it screws up an old type pilot. It's ability to fly gives it an edge over suits that can't. It's piercing weapons give it an edge if a unit is too slow to dodge or is dependent on shields. However some armor and the nature of things like Raigo's beam deflecting shield may even the odds in some instances. 

 Also for Arthanus's character I wouldn't say he is a super newtype as much as a newtype whom has had a lot of experience fighting opponents with his powers like Amuro. He can't use his newtype abilities to transmit thoughts and he can't use it to put a suit back together. When I think of super newtypes I think of Judau Ashta. The dude is one of the most legitimate aces in the whole of the gundam franchise. The whole thing with the trans-am was for the purity of plot convenience and that all it was besides Reve being a horrible pilot in the sense of keeping herself under control. Also I have never bashed on Sughito's suit intentionally. I have stated that there are things I am limited to do in the roleplay due to the nature of sandrock being a land unit which is why I made Rondo appear specifically for Sandrock to have a challenger that can damage it slightly while still not able to beat it outright. And the whole deal with some suits being able to fly is for the same reason that Puru is able to use her funnels in atmosphere. This world is not normal and it is not Earth clearly. What it is will be revealed later.