Question: I'm having trouble finding the command that would match `%` in normal mode. Or any command for that matter, i.e. `yy` to `:yank`.

Basically what I'm trying to do is make a oneliner like so,
`:s/this/that/g | yank | undo | /* Move down one line */ | /* % */ | paste`

Answer: 
You can do normal mode operations in command mode with normal/norm.

For example, to yank the current line, you'd want `:norm yy`.
You can move to the next `%` character in normal mode with `f%`, and just before it with `t%`