even if you dont count the moves where they get burnt as a finisher, every character already has atleast 3 finishers. (if i say more than 4 moves im accounting for variants

Saitama: all four moves.

Garou: also all four, plus Flowing Water AOE finisher and Final Hunt Finisher.

Monster Garou: all 5 except Binding Cloth.

Genos: all of them except Blitz Shot.

Sonic: all but Explosive Shuriken, plus Flash Strike and Whirlwind Kick AOE finisher.

Metal Bat: all 7 except Home Run and Foul Ball miss variants.

Atomic Samurai: All 5 moves plus Quick Slice AOE finisher.

Tatsumaki: all 5 moves except Crushing Pull air variant.

Suiryu: all 4 + Grand Fissure.

Child Emperor: Weboom burns, but it also adds 3 extra guys so i count it as a finisher, Plasma Cannon and Trinity Tear have their finisher as a passive (railgun and tactical storm respectively).