"I fused all heroes to red"
Here I would like to ask a burning question: I have all my main heroes' gear at orange+2 modded to max stars. It was goddamn expensive to do. If I were to perform fusion to Red, would all these upgrades be discarded, and the character treated as if their Orange+2 stage was passed with zero upgrades? Because then I would like to know, does a naked Red character have higher stats than Orange+2 with max stars? If not, then going to red right now is a mistake. Does it even unlock a new skill?
You are correct in that fusing actually weakens a character. The act of fusing a character does not make the hero stronger. It just allows you to equip the next level items, which are what strengthens the hero. So if you have O2 enchanted, fusing to red only causes a loss of all the enchantments with zero gain elsewhere. When we went from purple to O then O2, word was you needed two or three items to equip to offset the loss of enchantments. Many of us stayed purple until we could make the jump straight to O2. Same should apply to fusion from O2 to red.