Improvised Attacks

You aren’t limited to Moves and simple Struggle Attacks in a battle. Oftentimes, you will attempt a maneuver that isn’t strictly outlined by the rules, such as using a rock as an improvised throwing weapon or attempting to push a nearly-felled tree onto an opponent.
The general rule here is that if the maneuver isn’t very limited by resources or the environment and is easily replicable, then it should have a lesser effect than any well defined counterparts in Moves or Weapons. A penalty to AC and Damage Base is often appropriate, and for non-damaging attacks, a reduction in the attack’s effect.
For example, it’s easy for any Trainer to grab a handful of dirt or sand while in the outdoors or even from a prepared bag to throw in an opponent’s face without knowing the Move Sand Attack. Rather than Sand Attack’s effect, your GM might treat this as an AC 5 attack that reduces a foe’s Accuracy by -2 until the end of their next turn.
In the case of improvised attacks with common implements that have a Type association such as throwing a rock or snowball, you would nonetheless treat them as Normal Type attacks in most cases because it otherwise becomes far too easy to gain Type coverage. A thrown rock does Normal Type damage for the same reason that Geodude can do Normal Damage with a Tackle Move. It takes a certain oomph behind an attack to give it a Type.
On the other hand, if you’re trying to hit someone with a torch to deal Fire Type damage with your Struggle Attack, your GM could rule you can do so – but only once before the torch breaks from the impact.
More elaborate improvised attacks may warrant a Typing or even emulating an effect similar to many Moves. For example, if you push a boulder on a mountain in a way that it unleashes a landslide on your foes, your GM might rule that as a Rock Slide attack and let you roll as if using the Move. A GM might require SKILL Checks to be made to pull off some of these trickier maneuvers and base the attacking stat’s value off of these Skills. For example, a Survival Check to trigger the landslide and then Survival Rank times three for Attack Stat. Given that this kind of situation is likely rare, hard to repeat in the same battle, and difficult to deliberately set up, it’s a good idea to reward players for taking advantage of the environment in this manner.