Think about the associated object(s) that best represent(s) those moves, or a clever wordplay that can succinctly convey the information (keep in mind that word play will likely not translate into other languages, and this'll add extra work if you want your game to be localized for some other country(or countries)). Some suggestions:
- Shoe/foot for kicks, rotated and presented at an angle to convey the motion of the action
- Circular suburban residence for "roundhouse" kicks, note this is likely an english-only functional symbol
- Fist for punches, simplified and cartoony as deemed necessary (think pacman gloves, for example)
- Open hand for chops, think a "paper" move from rock, paper, scissors. Rotate and angle as necessary to convey action, much like the shoe
I am not sure how broad of a range of moves you'd like to represent, which is why I included suggestions for both kicks (general) and roundhouse kicks (specific), for example. Also! My suggested symbol for roundhouse kicks serves as an example of the visual pun technique that you may be interested in using, just remember again to keep in mind that this method is NOT language-agnostic.
Hope this helps! If my suggestions seem too complicated for the player to draw, you absolutely could do something incredibly abstract, like lines or basic shapes. If you choose to go down this route please reference Lost Magic, a 2006 game for the Nintendo DS; and Magic Cat Academy, a 2006 (COINCIDENCE????) game that's playable in web browsers. There is also, as I recall, a similar "draw things to do things" game made and published by Nitrome you can search for if you feel like the first two references I suggested are not enough for you to make a decision. :- )