I found this trick while doing my low% run proof of concept (which is why I don't have dash at level 5 in the video below). You can use it to gain as much height as you want, using mosquitos:

If you use only one mosquito it doesn't work, as they bob down when you jump and you end up losing height. With three it's very easy, once you've got them clustered underneath you. I have no idea if this is useful in any of the current routes. You climb fairly slowly, but it might be handy somewhere.

Recently I've been interested in what a low% run for Deadcore would look like. I think that whatever sparks you want should be allowed, as they are just alternate routes through a level. This is open for discussion though. My initial route only uses 4, of which I believe only 2 are absolutely necessary. Logs and tracks are irrelevant, as its faster not to get them anyway.

So, this just leaves abilities and upgrades. I've done a proof of concept run which shows that it can be done with no dash, no blast, and no upgrades. I'm pretty confident that this is the minimal set - a run that doesn't use the SwitchGun seems impossible, likewise for G-Mod.

The route is very difficult, but quite cool. There are quite a few little tricks that are unique to this run that you have to do to work around not having dash. If anyone's interested I'll try to get a full recording of it. My initial run took about 3.5 hours, but this includes figuring out the entire route. Also, the route could probably be improved with what I learned from the first run. I would conservatively estimate maybe an hour for a decent run. However, even getting a "decent" run would be hard, as there are lots of difficult tricks that can take a long time to pull off. ¤Lots¤ of superjumps and several megajumps are necessary. Megajumps aren't nearly as game-breaking in this category though, as without dash they are much less powerful.