I've said this before somewhere on the forum. Contrary to the popular belief here that Smoker now has no chance against Luffy, I believe he is still able to fight equally with Luffy.
Just before the timeskip, Sengoku opted to step down from his post as Fleet Admiral on
this page and Kong asked him if he could retain his title for the purpose of the training younger marines like Garp was doing with Helmeppo and Coby. On the very next page after Sengoku agreed to spend his remaining years doing that, we are shown Smoker request to be moved to G5 in the New World in which Ao Kiji replies that he was going to negotiate the transfer with Sengoku.
At the current level Smoker was on, there is absolutely no way he would have survived in the New World. He would most definitely have been killed. Because of this, it would make sense that when the request was brought to Sengoku like we were told, Sengoku would not have approved of it. He instead would have probably decided to train Smoker until he was ready to go into the New World, to stay true to his word that he was going to spend his remaining years training young Marines. It would be similar to how Luffy wanted to continue his journey but Rayleigh told him that the incident in Shabondy would only repeat itself at the current level he was on.
If we put the fact that Sengoku agreed to train the younger Marines, with the fact that we were shown that Smoker wasn't ready to go into the New World just a page later, it can be accurately deduced that Oda is planning on having Sengoku train Smoker. Since Garp is training Helmeppo and Coby who are relatively important characters in the manga, Oda is probably not going to make Sengoku train a new character that we have not heard of and instead would most likely have him train someone important who is also still growing. Having Sengoku train Smoker would also be a good way to keep Smoker on the same level as Luffy since their relationship is supposed to mimic that of Roger's and Garp who were more or less equal in strength.
So to put it simply, Luffy was trained by Rayleigh which would have given him a major advantage over anyone that was not trained by someone of that calibre. Sengoku is no weaker than Rayleigh if not stronger. I think Oda intends on keeping Smoker and Luffy on around the same level like Roger and Garp, so it would make sense that Smoker was also trained by someone of similar strength to the person Luffy was trained by. Therefore I believe Sengoku trained Smoker over the two years which by all intents and purposes would make Smoker similar in strength to Luffy.
