I was bored. So here, have a hypothetical Classic Mode for Dee.
Title: The Arena
Theme: Each battle is similar to that of a battle in The Arena's Super Star version. Specifically, the Spring Breeze bosses and Mid-Boss All-Stars
Stage 1-Ivysaur (Represents Whispy Woods).
Stage 2-Popo & Nana (Represent Lololo & Lalala).
Stage 3-Bowser Jr, Ryu, Incineroar (Represent Mid-Boss All-Stars)
Stage 4-Big Pichu (Represents Kracko)
Stage 5-King Dedede (Represents... King Dedede)
Stage 6-Meta Knight (Represents... Meta Knight)
Boss-Marx (Represents... Marx)