I think I figured out a way to make them playable, though it might sound a bit complicated. Think something along the lines of FighterZ Ginyu, with Battle Japan being the main hero you control. Here's a mockup moveset:
>Passive: Ranger Rotation (certain attacks change after every use, switching out a ranger)
>Space: Wall Run
>Left Click: Karate (attack opponents with a barrage of chops and kicks)
>>Left Click while Dashing: Dynamic Entry (close in on opponents with a flying kick)
>Right Click: Battle Spear (Block an opponent's attack with your spear before doing a mid-range counterattack)
>Shift: Command Bat Summon (summon a ranger in sequential order to attack with a weapon)
>> Battle Whip (Battle Kenya jumps in and restrains the opponent)
>> Battle Sais (Battle Cossack jumps in and combos the opponent)
>> Battle Fencer (Battle France jumps in for a quick stab, stunning the opponent)
>> Battle Knives (Miss America jumps in and throws her knives at a distance)
>E: Battle Dance (summon a ranger to do a dance to buff yourself, doubles as a short-range attack)
>> Kenyan Tribal Dance (boost your overall speed temporarily)
>> Soviet Hurricane Kick (increase the damage output of your attacks temporarily)
>> French Flamenco (automatically avoid oncoming attacks temporarily)
>> American Disco (heal a small amount of your HP)
>Ultimate: Penta Force (a star-shaped boomerang that becomes a missile launcher after returning)
>Ultimate (after using Penta Force): Battle Fever Robo (temporarily control a mech to gain the advantage)
>> Space: Rocket Flight (slowly fly around)
>> Left Click: Swords Fever (attack opponents with a combo utilizing giant kunai)
>> Right Click: Chain Crusher (attack opponents with a chain whip)
>> Shift: Attack Lancer (dash forward with a giant trident)
>> E: Karatake Wari (a long-range attack using the lightning sword)
>>Team-Up: SP//dr Enhancement (Peni attatches SP//dr to Battle Fever Robo's shoulders, shooting cyber-web clusters as they attack)

What are their chances of being added?