If the king had not been wounded, the czar might not have moved his army toward the Swedes, so there might not have been a battle at Poltava.
Anyway, the Swedes lost the battle primarily through a breakdown in communication among the leaders, and a following indecisiveness. Otherwise, the battle could have gone either way.
An amusing fact seems to be that the Swedes never considered that they might lose the battle, so they had no preparations for such an event. They had crushed a numerically superiour enemy army every year for a decade, so they had some basis for that approach.
But now, the question was to have the king commanding the battle. I have no idea, really. Perhaps the same battle plan is followed, but here Roos knows that his column only shall pass the Russian forts, and then all the Swedish foot attacks the Russian camp early, and the cavalry and artillery are also at hand for significant support. Now parts of the Russian army are confused and defeated, while the rest withdraw as well, so the Swedes stand as victors on the battlefield and secure their hold of this small part of the Ukraine for the rest of that season.
The czar is less secure against the Russian opposition, but nothing decisive in Russian internal politics happens that year, so he has an even better army to put in the field in 1710, while the Swedish army then has withered some in its core, while getting a larger force of semi-reliable local troops, so the grand battle of 1710 is less favorable to the Swedes. They may still win that battle, but might be severely weakened, making further offensives out of the question, so the campaign has to be ended, and a return west is necessary.
The Swedish general Krassow has tried from Poland to connect with the Swedish main army in 1710, but has been defeated by the Russians along the way, and so has had to withdraw west.
