I noticed most runs use Normal Mode but the record is on Easy Mode. Should they not be separate? I don't want to play on Easy Mode.
it doesn't really matter what is used, it's your preference.
It does matter because Easy Mode takes less hits to beat the bosses. So to get the fastest time you have to play on Easy Mode, which I don't want to. And there are lots of other runs on Normal Mode too, unfair to compare them.
The decision to allow easy mode was relatively recent, so a lot of older runs were done on normal mode when it was required at the time.
After discussion in discord, we decided to allow any difficulty for runs - this means that the option to swap difficulties midrun is a possibility, and goes in line with the goal of speedrunning - beat the game quickly. Limiting runs to strictly one difficulty inherently restricts speedrunning options. One relevant example includes swapping to normal mode for egg rocket skip for tails, because the easy mode version is much less reliable and/or more difficult due to the removal of a specific enemy. This decision was made for advance 2 and 3 as well - in fact, it's almost worth swapping from easy to normal mode for egg utopia zone for amy in advance 2
If you want to do runs on normal mode then feel free to - but you'll soon realize that for bosses, it really doesn't add much besides just extra luck compared to easy mode - yet, the gameplay differences also aren't different enough to warrant an actual category split. If you want to discuss more, then feel free to join the discord and ask about it.