Team Battle

Upon selecting this option, you'll be greeted with this screen telling you how much experience you'll gain if you win and which Robot Masters you'll be fighting against:

For 840 experience, a fight with Blizzard Man and Plant Man

After pressing the enter button, you'll have to choose a maximum of three of your characters to fight with - I've chosen Mega Man, Wind Man, and Centaur Man here:

Notice the text over each character - the order of selection determines what stat buff each fighter will get

After a brief title card for the current stage...

...the fight begins. To my knowledge, there are no controls; every action is done automatically. One character will open with an attack, like so:

Mega Man going for it with a four-power attack against Blizzard Man

Occasionally, the character that just attacked will go again, but most often the opposite character will attack:

Blizzard Man hitting Mega Man with a 19-power attack

The majority of attacks will hit your opponent (and vice versa); however, there is a chance that you or your opponent can block (I've found this chance steadily decreases as you level up and the opponents scale to match):

Mega Man's attack harmlessly plinking off Blizzard Man

Note that the symbol and letter on each attack can vary in addition to the number indicating power; they indicate what element the attack is for a type effectiveness system - if the Robot Master is weak to the indicated element, the damage output of the attack is increased. I don't have a definitive list of type effectiveness, but your best bet would likely be to check the weapon effectiveness against each Robot Master for your choice of Rockman game.

This cycle goes on until either team has had all its members defeated; if you lose, you won't get any experience and are sent back to the main menu:

However, if you win you get the amount of experience previously indicated, albeit divided by how many characters you have in your team and distributed individually to each member:

The team gaining enough experience for Centaur Man to level up - I've found that leveling up happens very often after battles

After every fight, there is a random chance you'll be presented with this screen that flashes by:

This screen goes by so quickly, this was the best picture I could take - sorry!

This means that you've gotten a new Robot Master (natch). After this, you'll be presented with the Robot Master you've obtained with the option to flip through its statistics with the up and down buttons:

Pressing the enter button here will pop up a selection whether or not you want the Robot Master:

Choosing no here will have the game move on without doing anything, while choosing yes does one of two things - if you have less than eight Robot Masters on hand already the Robot Master is automatically added, but if you already have eight the game will ask you to choose one to replace:

After you choose one, this confirmation screen will show up:

Choosing yes will replace the selected Robot Master, while choosing no will send you back to the selection menu (remember that you can exit this menu by pressing the up button). Once you're finished, the first screen from the beginning returns to tell you the Robot Masters for the next stage (notice that the amount of Robot Masters has gone up to three):

For 765 experience points, a battle against Centaur Man, Flame Man, and Tomahawk Man - remember that I lost previously

This cycle of info-selection-fight repeats for three stages in total, after which you are sent back to the main menu.