You could do a spell Instant (No Spirit Bomb or Others Long Cast Spells) but it will drain all Ki and you could not Move or Power up like for 5 seconds.Gohan did something like instant kameha.I know he said Ka-me-ha-me-ha but it was almost instant.
The second (maybe another Fan suggested) if you're hp is low like 1-50 and you eat a Senzu Bean you will gain and some Ki Power like 10.000 or more(Saiyans only xD and maybe Cell because of his Saiyans Cell's)
Third.If you get punched with a big power you could pass trough a mountain and get some extra damage(if it could be destroyed it will be awesome if don't still cool)
For Goku Only...If it's teamplay and you target a Ally you could Use Instant Transmission on him and get at him.
The second (maybe another Fan suggested) if you're hp is low like 1-50 and you eat a Senzu Bean you will gain and some Ki Power like 10.000 or more(Saiyans only xD and maybe Cell because of his Saiyans Cell's)
Third.If you get punched with a big power you could pass trough a mountain and get some extra damage(if it could be destroyed it will be awesome if don't still cool)
For Goku Only...If it's teamplay and you target a Ally you could Use Instant Transmission on him and get at him.