Shoryuken forum user mumu recently went snooping around the Japanese site for Tatsunoko vs. Capcom and uncovered some interesting items. Within the source code of the character section of the site, mumu found lines of code hinting towards the remaining secret characters:

'images/oncharactor_btn_zero.jpg'
'images/oncharactor_btn_frank.jpg'
'images/oncharactor_btn_yatter02.jpg'
'images/oncharactor_btn_joe.jpg'
'images/oncharactor_btn_tekkabla.jpg'

So, aside from yesterday's Tekkaman Blade, mumu postulates that Dead Rising's Frank West and Zero from the Mega Man series are also going to be in the game and, on the Tatsunoko side, we'll get Yatterman #2 from Yatterman and Joe Asakura from Gatchaman. If you'll excuse us, we'll be crying in the corner, objecting once again to the lack of Phoenix Wright.

Read more at Joystiq