by 'kicking butt', I would include outright victory. OTL, Brazil and Argentina basically fought to a tie. The compromise was an independent Uruguay. An Argentine victory would mean they defeat Brazilian forces and push them out of Uruguay, and may even expand the territory to reclaim/claim portions of Rio Grande do Sul. They're not going to wank their way to huge portions of Brazil or otherwise put a serious hurt on Brazil. But, IMO, simply outright winning in Uruguay qualifies as 'kicking butt' (glibly speaking). Fighting to a tie caused enough trouble for Pedro. Losing the war amps up the trouble big time.
To get to that scenario, you have to stabilize/unify Argentina from the early years of independence so that they're stronger at the time of conflict. Of course, if you do that, Argentina probably doesn't encourage Luso-Brazil to take Uruguay to begin with (to get rid of Artigas), so there would be no Cisplatine War.