Slap a Swift Core on Dynamo Man and use Dynamo Bolt until everything is dead. This should give an S rank.

Could you make a "Player Battle Team"? Like, have an option for the player to set their player battle team of robots and doctor for others to fight rather than what seems to be the first six robots in their lineup, sort of like the Battle Box in the more recent pokemon games. I think that would change the monotony of just Dynamo Bolting Megaman for 1000 battles, and it would kind of make the "Player Battles" feel more like "Player Battles" rather than feeling like beating someone who just started. Also, I think that it would be cool to have rematches with other players. I don't know how that would possibly work, but I mean, when a really powerful Robot Master comes out (such as Crystal Man), there's a possibility that that robot was put into some players teams, right? I don't think rematches should give points though.

I know this isn't actually the place to post this, but could you make a "Player Battle Team"? Like, have an option for the player to set their player battle team of robots and doctor, sort of like the Battle Box in the more recent pokemon games. I think that would change the monotony of just Dynamo Bolting Megaman for 1000 battles, and it would kind of make the "Player Battles" feel more like "Player Battles" rather than feeling like beating someone who just started. Also, I think that it would be cool to have rematches with other players. I don't know how that would possibly work, but I mean, when a really powerful Robot Master comes out (such as Crystal Man), there's a possibility that that robot was put into some players teams, right? I don't think rematches should give points though.

Finally claimed my crown for getting 1st place in the leaderboard after defeating about 1000 people with only Megaman in their team! Yay.

If I use a Forge Circuit on Wood Man, is he still resistant to water?

@Salt : Sorry, I didn't realize, as all of the current challenge missions are 6 turns long.

@Salt : If your enemies are dead, then you wouldn't need to heal at all, because they won't damage you.

@Salt : On the 6th turn you will fail the mission anyways, meaning that you will have near invincibility without needing to level Kalinka up to whatever level she sells the circuits.

@Anime Man The first sentence is EXACTLY why I used cores rather than circuits. I COULDN'T SEEM TO FIND ANY ANYWHERE, until today, that is.

I'm pretty sure it might have something to do with Kalinka's level, because I just unlocked them after buying a ton of things and showing her stars, which boosted her level up from 68 to 86, but I'm not 100% sure about it.

I found a rather cheap (as in, NO NEED TO GET stupid CIRCUITS which BTW how do you get them) way to get Fuse Man, Dynamo Man, and Aqua Man.

Get Roll(ABSOLUTELY CRITICAL) and a Copy Core robot maxed out, and with Dr. Wily for extra damage.
Equip both of them a core with whatever element you are dealing with. (Fuse Man & Dynamo Man are Electric, Aqua Man is Water) This is to negate their lethal moves Dynamo Bolt, Water Balloon and Scramble Thunder. Also, for Dynamo Man, don't worry about Rain Flush, after enough tries, which is probably less than 5, you will get it.

Roll ABSOLUTELY needs Roll Swing, Attack Mode, and Attack Swap.
Mega Man/ Bass / Proto Man ABSOLUTELY needs Bass Crush, and Bass Baroque.

Turn 1: Roll uses Roll Swing. This gets rid of the stupid block in front of the target robot.
Turn 2: Roll uses Attack Mode.
Turn 3: Roll uses Attack Swap on Bass.
Turn 4: Roll switches to Bass. Bass uses Bass Crush on target robot, to increase damage.
Turn 5: Bass uses Bass Baroque on the target robot.
Turn 6: Bass uses Bass Baroque on the target robot again.

You get the robot, but you will fail the mission. Have fun getting these guys!

Some similar strategies to what help said,
Astro Crush on an Impact or Space Robot with a Reverse Module (raises attack rather than decreasing)
Dynamo Bolt with Buster Module to instantly fire off the bolt
and of course, Rain Flush with any water core robot
I highly recommend Final Destination III with Wily as the player for extra damage, using Dynamo Bolt to fry all the robot masters, giving 2500+ exp per robot master, depending on how many you have brought. I also recommend bringing 1 extra robot at a time, because that'll give about 40 levels to the robot that you are training. You can also change the robots that are in Final Destination III by changing the player fields on the Players tab found next to the Robots tab. The robots that appear correspond to their respective field.
To further expedite training, I recommend changing the Preserved forest (Wood Man) and five other fields that isn't the Waterfall Institute (Bubble Man) to Arctic Jungle (Ice Man) , Serpent Column (Snake Man), Clock Citadel (Clock Man),Submerged Armory (Dive Man) and Magnetic Generator (Magnet Man). This will make Dynamo Bolt even more lethal, along with getting more of those sweet field experience bonuses.
If you plan on using Astro Crush, change Abandoned Laboratory (Quick Man) and three other fields that aren't Sky Ridge (Air Man) to Abandoned Warehouse (Cut Man), Spinning Greenhouse (Top Man), Rusty Scrapheap (Dust Man), and Rocky Plateau (Hard Man). This will make Astro Crush even more lethal while raising the field experience bonus.
For Rain Flush, there really isn't much, use [Atomic Mill (Heat Man)]{fire} and change Waterfall Institute (Bubble Man) to Lightning Control (Bright Man), and change Preserved forest (Wood Man) to something else that also isn't going to resist water, such as Toad Man or Spark Man.