These are various things I'd do to improve Atlas. *Edit: As I was trying to sleep (And failing) I brainstormed a way to improve tectonics.
1) I'd change his attributes to have no shields with increased health, 150-200 is what I'd go with at base. Possibly more armor. Atlas is meant to be a titan and having the base line default health just seems unworthy of the title.
2) Ultimate Changes - I'd make it an exalted rock (Crystal for deluxe) fist type weapon, similar to his 1, it'd dash to your enemy while delivering a powerful AoE punch. Upon activation and for as long as it is active, two rumblers would be summoned to fight til death or deactivation of the ability. With it being an exalted weapon, you'd be able to mod it separately and the rumblers would use the mods. Reason for this is because rumblers by themselves with no scaling is a very terrible ultimate ability, doesn't even deserve to be called an ultimate. This would add much more to the ability.
3) Rubble Passive - No mechanic or stat changes, for his passive, I'd make it cover the whole body to become a full on rumbler when around 80% rubble. For the deluxe skin it'd grow crystals instead of rocks. There would be an option to disable rubble visuals under the appearance tab in arsenal. Reason being fashion frame.
4) Deluxe Weapon Implementation - Allow fists type weapons to use the karst deluxe weapon skin. Reason for this is because the Tekko, a fist type weapon, is Atlas' signature weapon and they cannot use the deluxe for Atlas. I shall not dwell on this further as I would go into a frustrated rant.
5) Deluxe Skin Effects - I would make it affect ALL of his abilities rather than just his ultimate.
6) Rumbler Changes - Give his rumblers more attacks that are not as slow and let them dash to enemies for a punch. It'd be pretty cool to see them do the special power stanced fist weapon attack from dark souls 2, a tornado of three punches with the third knocking down enemies. Reason for this is because it'd make them feel more like brawlers than just entities punching things in an unmotivated manner while also letting them actually hit things that decide to walk away from them.
7) Tectonics - His walls desperately need more damage reduction as in higher levels they get deleted pretty quick, making them mostly useless. I would remove the boulder mechanic and allow Atlas to place 3-4 walls without the augment.
8 - 😎 <-- remove emoji conversion (reason for this is it makes my list numbers inconsistent). Petrify Changes - I would change it so that instead of glaring at a group of enemies and petrifying them, it'd be a sort of fist slam, causing rocks to rise from the ground and coat the enemies in a 15-20 meter base radius. Reason for this is due to the gaze being somewhat finicky to use and sometimes not going in the direction you want, this change would make it far more useful.
9) Ultimate/4 Augment Changes - I'd change this augment to spawn four rumblers instead of two with the ranks of the mod scaling their attributes back to 100%. Reason for this is because the current effect is terrible, not worth using or even considering other than having a super sized rumbler. Call it "Rumble Royale"
10) Petrify Augment Changes - I'd give it a different effect, turning petrified enemies in lesser rumblers that have a duration and as they decay, they drop 10 rubble every 10 seconds, lasting 30 seconds. Affected by power duration. Reason for alternate effect is it'd be a good consideration for use, call it "Titan's Influence".
11) Tectonics Augment Changes - It would make Atlas only able to place one wall but activating the ability again Atlas uses up 100 energy (Affected by Efficiency) and sacrifices the wall for 800 rubble, half would be converted into armor, the other half into healing. Excess rubble from healing would be converted into additional armor, call it "Tectonic Plating". This would give Atlas a solid method of healing and gaining rubble.
12) Landslide Augment Changes - While this is a good augment, think I'd change it so the AoE from final combo punch petrifies enemies rather than ragdolling them. Call it "Earthen Wrath"
That is all, keep in mind Atlas is meant to be a Titan, these changes would make him significantly stronger and actually feel like one. Though I wouldn't consider any or all of these 'overpowered' as there are far better warframes for the job. And with these changes, all of his kit would be used often. As well as allowing for better fashion frame, whether you want to become a rumbler, grow crystals, or not have rubble have a visual effect thus possibly ruining your fashion. Been playing with him for nearly four years now and in the excitement of him chronologically being the next prime, I would love it if DE would look at his overall design.