The first melee super you get, I forget its name, but you can hold down the button to keep going, can end up doing not only a lot of damage, but can also net an insane combo. The only downside is that, unlike Super Ki Explosion, opponents are capable of vanishing out of it without bullshit NPC armour. I think there's also a regular Ki Explosion, as well. I've not found anything that can replace the Kaioken Kamehameha, though, in terms of damage, hit rate, or utility.