-Rivalries-
 
Twilight Sparkle (mlp) vs Harry Potter  
(magically gifted students, have defeated high-level threats in the past)
 
John Egbert (homestuck) vs Aang (avatar)  
(main element is the wind)
 
Finn & Jake (adventure time) vs Link (legend of zelda)  
(young swordsmen from fantasy-adventure settings)
 
Sonic the Hedgehog vs Rainbow Dash (mlp)  
(blue, attitude, known for their speed, have defeated high-level threats in the past)
 
The Doctor vs Dave Strider (homestuck)  
(both affiliated with time travel and utilize unusual-seeming objects to do so (The Doctor via the TARDIS, Dave via his Time-Tables))
 
Superman vs Luke Skywalker (starwars)  
(reference to YourFavoriteMartian’s Nerd Rage video: “and a Jedi could whip Superman in a fight, when i’m right imma laugh like (NERD laugh)”)
 
Marceline (adventure time) vs Kanaya Maryam (homestuck)  
(vampires, dual-purposed weapons (Marceline’s axe-bass, Kanaya’s lipstick/chainsaw))
 
Shadow the Hedgehog (sonic) vs Experiment 627 (lilo & stitch)  
(artificially created lifeforms that are the strongest of their kind)
 
Prince Zuko (avatar) vs The Pyro (tf2)  
(main element is fire, LOTS of fans)
 
Meloetta (pokemon) vs Hatsune Miku (vocaloid)  
(main element is music, kawaii-desu, reference to the Meloetta: Melody of Discord fangame)
 
Reimu (touhou) vs Dark Magician Girl (yugioh)  
(high-ranking magical girls in their own settings (Reimu as a Shrine Maiden, DMG as student of Priest Mahado in her past life))
 
Applejack (mlp) vs Hungary (hetalia)  
(independent to an extent (Applejack claiming to buck the entire orchard on her own in Applebuck Season but eventually caved and asked for her friends’ help, Hungary and Austria have long-since divorced but still treat eachother as a couple))
 
Vriska Serket (homestuck) vs America (hetalia)  
(egotistical, very few can stand them in-universe, but they have their fair share of fans IRL)
 
Flame Princess (adventure time) vs Katniss Everdeen (hunger games)  
(pun involving “girl on fire”)
 
Stitch vs Zim  
(main-title aliens debuting in the early 2000s)
 
King Sombra (mlp) vs The Lich (adventure time)  
(undead dark lords sealed away for at least a millennia (The Lich in amber beneath the candy castle, King Sombra in the northern ice))
 
 
-DLC Rivalries (AT SOURCE ONLY)-
 
Pinkie Pie (mlp) vs Kirby  
(pink, can eat seemingly endlessly, have defeated high-level threats in the past)
 
Draco Malfoy (harry potter) vs Eridan Ampora (homestuck)  
(wizardy rivals, opposing views on magic)
 
Lion-O (thundercats) vs He-Man (masters of the universe)  
(80s muscular swordsman icons)
 
Ganondorf (legend of zelda) vs Gunter (adventure time)  
(high-level evils (Ganondorf being the King of Evil, and Gunter being stated as the most vile creature in all of ooo))