Having officially completed the challenge, at long last, I can say with 100% certainty that this is doable, and I know all the boss strategies.
A game of Kirby Superstar Ultra's (NDS) game mode "True Arena" where:
~You may not use powers
~You may not guard
~You may not have or in any way use a Helper
~You CAN use the provided Tomatoes for life up
In essence, you're playing True Arena as if you were playing Kirby's Dream Land.
Are you pink enough for this challenge?