Really, it's all very simple. The Mega Man on the left is from about ten minutes in the future. He tells the Mega Man on the right, the one from right now, that he needs to go get Bass, just as Roll mentioned a few comics ago. So, in a few minutes, the Mega Man on the right will travel into the past to pick up Bass, and when he returns, he'll be the Mega Man on the left. Easy.
In fact, I'd bet that off-camera, the Mega Man on the left explains where and when Bass can be found, and exactly how to get past all of Dr. Wily's defenses to grab him. So it all makes perfect sense as long as you don't think about it too much and realize that this means that all of the information I just mentioned has merely been passed from one Mega Man to another an infinite number of times and never truly came into existance by any other means.
Oh, and somewhere between when he's the one on the right and when he's the one on the left, he'll completely grasp this time travel concept and come to terms with it, since the him from right now clearly seems to hate it.