"Elemental HERO Flame Wingman" + "Elemental HERO Sparkman" Must be Fusion Summoned and cannot be Special Summoned by other ways. This card gains 300 ATK for each "Elemental HERO" card in your Graveyard. When this card destroys a monster by battle and sends it to the Graveyard: Inflict damage to your opponent equal to the ATK of the destroyed monster in the Graveyard.
Shining Flare Wingman gains attack based on the number of Elemental HEROes there are in the graveyard. Fill your deck with Elemental HERO monsters and then use cards that send them to the graveyard to gain large numbers of attack.
Or run fusion gates rather than polymerizations. Shining flare wingman and shining phoenix enforcer are already over 3k if fusion summoned normally, if you use fusion gate you'll need to run cards that return the material monsters to the graveyard from being banished, otherwise they won't get their bonus attack.
I dont think fusion gate is good for flare wingman since it banished monsters instead of sending them to the graveyard cuz flare wingman has a special effect that can gain 300 atk for each E-hero in your GRAVEYARD.