In both games, Backup Bash costs 50 skill to use.
In the first game, Backup Bash can be purchased from BB once Bonnie has been unlocked. The cost for the skill, like all skills, is a small 5 tokens. However, on Night XX and Night XXX, Bonnie already has the skill at the time of his recruitment.
In the second game, Withered Bonnie comes with Backup Bash as soon as you defeat and recruit him.
In the third game, Springtrap learns Backup Bash at level 10. It functions the exact same way as it does in the other games.
Backup Bash is a skill which does a massive amount of damage. However, it has an 85% chance hitting with Cranky's Blessing (15% of hitting without Cranky's Blessing), so it's not always the most reliable skill in the world. Withered Bonnie uses it in the fight before obtaining him.
- The Backup Bash is similar to the Power Smash from Mother 3 as it has an extremely small chance of hitting and does a large amount of damage if it does hit, This is probably on purpose as FNAFB takes a lot of inspiration from the previous game to Mother 3, Earthbound.