Most of the weapons in Arms have a corresponding element. The effect of your charge punches, aside from additional damage, depend on what element they use. Here’s a rundown of all of them.
Charged Fire shots guarantee a knockdown on hit as opposed to a flinch, allowing you to take the initiative for your next move. A solid basic choice. (Trivia: Barq’s punch is fire element.)
Blows enemies away on hit. Only really recommended if your game plan involves actively keeping the other player at a long distance. For example, a parasol can blow away enemies who get to close to you and then put them back in range for your boomerang or missiles. Wind weapons are good in a Rush, where they create a huge tornado that’s hard to dodge.
Charged Spark shots freeze the opponent and take out both of their arms temporarily, leaving them unable to defend themselves. If you’re close enough when it happens, you might be guaranteed a grab off a Spark hit.
Frozen enemies slow to a crawl and can’t dash. This seems perfect for a grab, but they are still able to punch. Instead, hit them with a punch that they can’t avoid.
Explosive weapons, uh, explode. This attribute is great on long-range weapons, giving them some extra damage and blast radius. However, you need to be very careful with your explosives up close. Blasts from explosive weapons can damage you as well as your opponent. If your opponent stops your explosive punch as it’s starting up, it can explode in your face.
Here is a video of me intentionally attempting to make this happen. As you can see it’s fairly rare.
Stun weapons have a simple, subtle effect: they just stop the other player from doing anything at all for a brief moment. You’ll see them flash orange very briefly if it worked. Unlike Spark and Ice, the enemy won’t be stunned for long enough to open them up for a hit: Stun just delays them a bit, allowing you to set up for the next hit.
Only the unique Blorb has this element. When hit with a charged punch, the opponent’s screen will be blocked (like with the ink in Mario Kart.) This is a simple but powerful tool. A blinded enemy has only the slightest idea of what you are doing and can only react by guessing. Among other things, force your blinded opponent to choose between guarding against a normal attack (with a block) and a grab (with a punch).