I thought bronze since it's an easy marker for track completion and it's possible to earn all bronze medals without pickups on, whereas there are some tracks where gold and/or diamond may not be possible without them. Medals also can't be earned if any in-game cheats are enabled.

Pickups are seeded in Time Attack mode, this means that they are predetermined-- each item will spawn in the same place every time for all players, eliminating RNG and allowing for more creative routing. Basically every item spawnpoint was given a special value for Time Attack that only lets it spawn one specific item. The items also don't regenerate after being picked up until the track is reset.

Also, I'd like to know if the bonus tracks are required for the current full-game category, it's not totally clear since they're not listed in ILs.

I think these could be good formats for full-game runs. "33 bronze medals" would include the battle maps which have a target breaking mode as well as the "bonus" tracks. Runs with "Item Pickups: ON (seeded)" would be really fun to watch imo.

33 Bronze Medals (No Pickups)

• Earn 33 bronze medals in Time Attack mode, begin the run with 0 total medals.
• "Item Pickups: OFF" on every track
• Cheats and lag abuse are not allowed.
• All other skips and techs are allowed.
• Video is required for this category.
• Timer starts when you select your first track, ends as soon as the "Bronze" medal counter reaches 33.

33 Bronze Medals (Pickups)

• Earn 33 bronze medals in Time Attack mode, begin the run with 0 total medals.
• "Item Pickups: ON" on every track
• Cheats and lag abuse are not allowed.
• All other skips and techs are allowed.
• Video is required for this category.
• Timer starts when you select your first track, ends as soon as your "Bronze" medal counter reaches 33.