In the 18th century, three of the electors (Prussia, Hannover and Saxony) of the Holy Roman Empire ended up with kingdoms outside of the empire. The Wittelsbachs (both in Bavaria and in the Palatinate) tried for this on two occasions (the kingdom of Bohemia and resurrecting the kingdom of Burgundy in the Netherlands), but couldn't seem to make it stick.
Until 1731, there were (male) Swedish Wittelsbachs, although the line ended with the death of Queen Ulrika Eleonora a decade later. Said Swedish Wittelsbachs, belonged to the line of Counts Palatine of Zweibrücken, senior to the line which later inherited both Bavaria and the Palatinate.
Now, we all know that the Electoral Palatinate was inherited successively by several junior branches of the family several times (Pfalz-Simmern (which was a junior line to begin with) to Pfalz-Neuburg in 1685, Pfalz-Neuburg to Pfalz-Sulzbach in 1742, and Pfalz-Sulzbach to Pfalz-Zweibrücken(-Birkenfeld) in 1799). If the Swedish Wittelsbach line had continued, they would've inherited the Palatinate (and probably Bavaria) then on the death of Karl Theodor, instead of Maximilian I/IV of Bavaria.
So, what if the Swedes were actually to somehow wind up with the Palatinate during the mid-18th century? Obviously this requires a butterfly in the 17th/early 18th century of Sweden, since we'd need to let the male line continue (either through Carl XII having a son/surviving brother who can continue the claim when his cousin, Gustaf Samuel Leopold dies in 1731, or through Gustaf marrying somewhat differently (his first wife was menopausal by the time he wed her, and his second wife was morganatic from what I can make out)), but I could be overlooking a bunch of stuff (like the butterfly net that would need to keep one of Karl Theodor's OTL brothers-in-law from surviving, or something like that).
Which is part of why I made it a AHC? as well as a WI.