Reasonable. However Obito's Mokuton, it appears you've ignored. Obito reacted to Ay.. I don't see how he wouldn't be able to do so against Tobirama who's Hirashin no Jutsu falls short of Minato's employment of the technique who is small bar above Ay.
Pity thy argumentation. >.> 'Spected more from you.
Katon: Bakufū Ranbu. Such a technique is Katon displayed on an immense scale, rivalling Madara and matching the Jūbi's size. Suggesting Obito didn't possess Katon: Bakufū Ranbu, is erroneous. Subject: Rin'negan. Such is falsity as we've seen Obito gain the Rin'negan.. He was laying dormant during the whole time span from completing his battle with Konan and entering the Skirmish with Gedō Mazō. No time frame suggested he was training... If in fact he was, where? All regions that he appeared within, he was in closed refinery near Zetsu or Gedō.. Why shall he risk harming them?
Next, we haven't seen Obito utilize Katon on such a scale, prior to the acquisition of the Rin'negan. However, the reasoning being, the scale of such fights and the intent. We've seen Obito fight Konan and Kabuto. Against Konan? Obito's Intentions were to decipher the location of Nagato's Corpse. Why shall he go all-out upon a sub par opponent? Katon: Bakufū Ranbo.. It is a large scale technique. Being in such a close proximity with Konan results in the Katon not reaching full potential prior to the offensive being inflicted upon the enemy.. Why shall he use it? It being small then expanding as well as requiring Obito to go tangible is a completely idiotic technique in such a time.
Rin'negan doesn't enhance the ability for certain elements... Simply allows the bearer to learn them all. Nothing suggests the Rin'negan would let Obito do such. Against Kabuto? He was inside his Mountain Grave Hideout... Why harm it against someone you reckoned was weak? Outrageous to do such. Against the Edo Tensei? Why shall? Small Proximity.. Obito appeared to be fine with fighting them if it came down to such. In addition to such, as soon as Kuchiyose: Edo Tensei was performed, negotiations began.
We've never seen Tobirama utilize Hirashin no Jutsu as a living being.. So, he mustn't have it. We haven't seen Hashirama utilize Mokuton: Kajukai Kōrin.. So he doesn't have it? We haven't seen Minato employ Kage Bunshin no Jutsu.. Heck, we haven't seen Tobrama utilize Kage Bunshin no Jutsu as a living person, so mustn't have it? Stating Obito doesn't possess Katon: Bakufū Ranbo prior to Rin'negan or claiming it's simply 'speculation' is absurd.
Obito Mid-High Difficulty. Tobirama has the potential to win if Obito sends a Kage Bunshin to the Kamui Dimension and intends on ever going intangible. How does he counter Suiton? Katon, Suiton or Kamui. Hirashin? His features with it aren't remarkable. He needs to mark Obito.. He doesn't have a mark on him and shan't as Obito can simply phase. Tobirama can utilize his Kenjutsu-Hirashin correct. No, he shall go straight through. In addition to such Mokuton shall be quite assisting in such a situation. Question: Can Tobirama land a physical attack upon Obito? No. Can Obito. Yes, via teleportation. Tobirama is a sensor and shall attack, basic Katon shall reel him back followed by Bakufū Ranbo. Tobirama hasn't show features to travel extremely far distances to avoid such. Tobirama hasn't showcased Suiton to match Obito's Katon, even when enchanted from such shown against Hiruzen.
Simple Kamui will defeat fodder Edo. Obito can teleport to the Kamui Dimension and cast Genjutsu to prevent any further harm. In addition, Izanagi.