Okay, about time somebody did this. This is a list of secret routes I've recieved and how they are recieved. If I missed one please let me know!
Dabura - Beat Racoome with ultimate attack
Janemba - Go left then beat perfect cell with Gogeta's Stardust Breaker without items equipped
Turles - Beat Frieza with Tarble's Ultimate
SS3 Goku - This one confuses ppl the most, no...it's not the Stardust breaker. You must defeat the third enemy with at least a 20 hit combo. Before you break your controller...use Burter's ultimate attack, does mega-damage and is 30+ hits.
Bojack - Beat Gohan with Vegeta (Scouter) ultimate attack
Meta-Cooler - Beat Goten while in Raging Soul
Natural Goku - Beat Bardock with any super attack
Super Buu - Beat go left, then beat kid trunks with SS Goku's meteor smash
Frieza - Beat Android 14 with Meta-Cooler's finger blitz barrage
Cooler - Go right, then beat Kid Trunks while in Raging Soul