If your talking bout gaara in the sand beast form "mini" version (( not giant mode )) after you get ALL the people you just move the cursor over him hold the select button then select him while holding the select button.
Ohhh is that also how you choose different forms of characters too? Like if I wanted to start out with OTK Naruto in a fight instead of regular. But I have to have all characters to do it for the characters that have different forms?
to unlock the 1st and 2nd hokages you need to go to the building closest to the river and close to the village gates. then go in *side and talk to ebisu and take his quiz