Need help with how to animate this

Hey! So I’m trying to make a game with balloons and such that come with wacky physics.
Here is what the character looks like

I am trying to make a Headbutt animation for this game, but its already been found that just trying to animate it as a rig isn’t possible and procedural animation probably isn’t either because it requires the character being re-rigged through the script and would probably ruin the rig, so I don’t know how to going about this considering the 2 usable options have downsides. This rig only uses procedural footplanting for R6 but that is probably only for the lower body of the avatar. I tried tween the root but it brings the characters legs off the ground and its close to what I want but not what I want; I want the torso to be tweened downwards at a 90 degree angle without bringing the characters feet off the ground. If you guys have any idea how this problem can be solved please let me know!

Inside the player: