Having played a good bit of Gauss, I have to say, I quite like his abilities but they feel a little underpowered or lacking the oomph that they look like htey should have.
His mach rush is pretty lacklustre and and as it's his core ability, I would think it best if his other abilities augmented his mach rush such as the following:
Kinetic plating should absorb a set amount at each level with another percentage depending on power level which charges his redline battery which should be used for his other abilities with his mach rush and redline being the only abilities that use the energy pool
His thermal sunder just feels useless and I find myself struggling to find any point in using it but I like the idea of the hot/cold dynamic. So, instead of creating tiny AoE fields, how about augmenting his mach rush? Press and hold causes Gauss to absorb energy as he moves creating a super-frozen shell around him which equates to impact/ice damage to enemies he hits and depending on the power level, there's an increasingly higher status chance to cause freeze procs and additional ice/impact damage. Tapping his thermal sunder and then using his one should create sonic booms (explosions) that ragdolls enemies that he passes and inflicting high-status chances of explosions and staggering effects.
His redline could then boosting his other abilities depending on the charge state of his redline battery. As an example, when he rushes through with his mach rush, it should cause enemies to be dragged along by the slip stream causing greater damage to the enemies caught by them slamming into each other and then taking a set amount of damage depending on power strength, distance travelled and the number of enemies captured in his slip stream
His redline adds a deflection ability to his kinetic plating in the form of electrical arcs that can be combined with his thermal sunder ability to change the damage into radiation or magnetic damage.
His thermal sunder ability gains a crit chance to the damage but it runs down the redline battery at an accelerated rate that is partly negated by running/mach dash and kinetic plating.
As a side effect, his redline battery dissipating while no ability is in use should charge his energy pool.
For his mach dash, it should create shockwaves every time you impact an enemy causing impact damage and high-status chance of staggering that can generate a small percentage of redline battery
The way I see Gauss functioning relies on a careful balancing of speed and abilities to keep your redline battery and energy pool active and charging each other and generally buffing each other.