1. Nikki wins easily. Anyone who can do the slightest thing to a Moon Buster is already far above Part 1 top tiers.
2. Probably Nikki. He didn't get oneshotted by Goku, who's weighted self was implied to be above the base Garlic Jr. that stomped Kami.
3. Assuming Kami is as strong as his Movie 1 self, he wins, otherwise Goku wins.
4. Yajirobe wins considering he was shown about equal to Kuririn just before the end of their training, despite Kuririn at least being above 400 based on the combined battle power of 1,507 against the Illusion Saiyans.