Obviously, that is subjective, but there are a few things you could consider when thinking of ideas such as...
1. Good connections/similarities! (Example: A reason we chose Finn VS Iden Versio as a matchup is because SPOILERS! Both are ex-Empire/First Order characters who end up fighting for a greater cause)
2. How well their powers, arsenal, or abilities play off of the other's! (Example 1: Let's say character A can shoot fire from his hands, but character B can redirect fire. We could also say characters B can remove your soul, but character A can fight as a soul.) (Example 2: We could say both character A and character B have 3 different transformations in which they get strong. We could also say both characters excel at hand-to-hand combat)
3. How strong their rivalry is!(Example: Mario and Sonic do not have the greatest similarities, but the rivalry between Nintendo and Sony, + their fanbases, makes you want to see it anyway) (Other Examples: Naruto VS Luffy, Master Chief VS Doomguy, Pokemon VS Digimon, Star Wars VS Star Trek, etc.)
4. Good themes! (Example: Let's say we pick two old fashioned horror movie characters for a spooky Halloween themed battle. We could also pick a futuristic character and a medieval character for a Future VS Past themed battle)
5. Engaging character interactions! (Example: Perhaps you are simply curious what would happen if Light Yagami met SpongeBob Squarepants)
6. Contrasting personalities! (Example: Spider-Man and Batman have a great rivalry and solid connections, but Spider-Man is more cocky and friendly, while Batman is... not that. This could create unique character dynamics)
(when submitting your ideas for a future matchup, using some of these could make your ideas more interesting and potentially even convince us to do them)
We have recently put up a poll asking which one of the listed matchups you would like to see the most! Go check it out! ➡️
PMC Death Battle: Battle Match-up Vote (planetminecraft.com)