Early: bloop frontline (tank+50% def against reds).
Midgame: crow (ranged dps + 50% atk against reds).
Lategame: marine (ranged dps + 50% atk against reds).

If you have them:
Chocolat (black pikachu talent) – to heal bloops.
Okayu or bubba or suisei – to increase motivation recovery even more with “cymbal symphony” (when I reached 3-15 I only had okayu).

Do not destroy the flag early game or the duck will appear and destroy you.

You have to stall with a defensive comp, max motivation recovery (play each 1 talent in your party at least once), store motivation, and use it all at once for mass crows + marine.

This way when you destroy the flag you can put good ranged damage on the duck with crows+marine, and your bloops will tank.

Note:

By mass, means low cost mobs.

Your best bet is to level up the fodders to somewhere to lv 10 to 15.  If you able to get Wall as support item before 3-15, use it, it will help a lot.

The general idea is:
lv up the voltage > somewhere from lv 6 to 7 before destroying the red camp >
Make sure you have decent amount of motivation points > don't summon any unit (if you do have a wall, use it when all your mobs are dead, stalling the boss & mobs for motivation points)> let blue camp get destroy > summon all units (summon them when blue camp is low hp), including UR and then spam low cost fodder > then pray. > if dead, level up your units. Do it again. If almost killed boss, try again.

Best time does nothing (except making enemies stronger every minute by 10%), i just use wall for building up motivation. Wall is damn good.

Additional Tips:

1st point is my formation set up i have a variety of instrument and each of them gives different one so i can bump up my voltage pretty high early thus motivation economy is set i usually aim for level 5 or 4 early
2nd point focus my gold on fewer talent with the 8 in my formation only half of them is level 20 the rest is level 1 but you can still make do with less just have one that will tank most of the early game and your main dps that can nuke your enemies usually your UR DPS talent
3rd get as much trophy as you can getting those bonus damages are pretty powerful as they apply to all your talent and the motivation boost and starting ones are a nice buffs as well so i hope you took all your "new" talent option instead of just giving star to your talents
my strategy is summon nousagi which is fine with level 1 but i leveled him up recently(after 3-15) and make him delay the enemy that would attack your flag
after that you should have a decent amount of motivation to summon your tank before they destroy your flag in my case its assistant-kun(lv20) which cost 9 it deals decent damage(area attack too) and has a decent damage
the goal is get voltage lv 5 or 4 so i save up for my 1,2,2,4 talents all level 1 they are just fodder to boost my voltage but their instrument boost are pretty balance(def, speed, cdr both support card and talent) remember you gotta summon them so that they are all alive at the same time to boost your voltage lv to 4 or 5 your tank may die before they get summoned which is a reset for me but on 1st try at least try if you can make it
i dont expect them to survive but voltage wont drop even if they die so just save up for my UR which is Roboco shes pretty strong as her rapid attack would transfer to another target if the one she attacks gets knocked back or die so even thou shes single target she pretty much just clears the front-line thats attacking my base or flag the rest of the fight is just me waiting for the rest of my UR to be summoned(Fubuki & AZKi) then after i would just keep all my symphony maxed out and multi summoning my tank(assistant-kun) until the wall is broken
keeping nousagi summoned will boost movement speed so i lvup him later so he can survive longer and stop dying every hit on him.

Authors: Faulivia, FallenAmberCloud, RonMark.