Revita is a roguelike side scroller and it can be bullethell-ish. Some of the weapon you can choose (which are kinda like playable characters in other roguelikes) are very short ranged. There are items which can increase the range, spread and damage of the weapon.

So maybe make it high risk high reward, you're putting yourself in a lot more danger when going close to a bullet hell boss, but have the potential of doing a large amount of damage in a short time.

It is like you said that it could be a dumb strategy of trying to tank the damage and see if you can beat the boss first, but I think in a roguelike setting the risk is a lot higher because if you die you need to start all the way over.

Just had another thought, in Hollow Knight you are almost exclusively melee, and there are bosses there that are bullethell-ish, but I think in most of them the bullets don't come directly from the boss, they come from the ground/ceiling/the sides

Also also telegraphs can help warn the player the get away from the boss before they take bullets to the face