I'm not sure it creates South American superpowers, but my favourite option for South American great powers is one where Rio de la Plata and Gran Colombia somehow stick together. So you have one country in the south that's Argentina, Bolivia, bits of modern Chile, Paraguay and Uruguay, while you have one that's Ecuador, Colombia, Panama, Venezuela and bits of Costa Rica and Ecuador.
Chile could end up in a Texas-alike situation for Rio de la Plata; the main problem is keeping them united; the problem is that a lot of the leaders during independence failed at leading once back in civilian life. And this is the part where I kind of get stumped: Santander leading a "parliamentary revolution" against Bolivar could probably solve Colombia's problem especially if he kicks it during his attempted conquest of Peru, but I have absolutely no idea how you can get the united provinces to stick together...
In this situation, though, Peru looks rather bad: Brazil will filibuster its Amazonian provinces as it did IOTL (if the Platinians don't do it first) and will probably end up stripped of its far north and south unless it either becomes stronger or remains as a Spanish Canada.
An alternative position I could envision for Peru is one where the two surviving republics agree to split it 50/50, so Chile to RdlP and Bajo Peru to Colombia, but I have trouble envisioning this alternative in a way that doesn't strengthen Bolivar as a leader.
Full unity of spanish South America, though, would lead to a lot of problems and I have difficulty seeing how it could be done :/
Keeping Uruguay is easy. Keeping Paraguay is harder, as Paraguayans had a sort of regional identity that preceded their independence in 1811, and Buenos Aires hadn't the resources to submitt them by force. But they might have joined a Platiniean Confederacy (I think they even proposed it around 1811).
So, you only need leades in Buenos Aires to accept that granting autonomy to the provinces is the only way to go, and that the new country cannot be run as the Vicerroyalty was run (that is, with provincial governors appointed directly from the siege of the central power). The question is how to achieve this. Maybe if the American political model was more widely known in the region prior to independence???
Keeping Upper Peru (otl Bolivia) is harder, and might require force.
And then there is the question of how to rule such a country: if you only have Paraguay and Uruguay, you'd basically have a bigger OTL Argentina: once that looks towards Europe for trade, capital and immigrants, and who exports mainly agricultural goods. It'd be less centralised than OTL, but its key sectors would be the same. And socially, it would be rather liberal (by comparison to other Latin American countries), as it was IOTL. It would be a country that won't rely on force labour (Indian or African).
If you have Bolivia, that means you are adding a lot of mineral resources, but also a sociopolitical time-bomb. You're incorporating a populated region that relies on open or covered forms of Indian servitude. This region (plus one or two of Argentinian northern provinces) might stick toghether as a block, and vote for conservative politicians that support status quo. The might side with the Church, so you might not get the reforms in education and other areas that Rivadavia or Sarmiento implemented IOTL. And, if this is not solved, you might get a revolutionary movement.
On the other hnd, huge countries like USA or Brazil did well dispite having this kind of blocks in their South or their North (respectively), and so might do Argentina...