1. all stats are disabled in arena, except treasure tools which will contribute 10% of their ini into arena. assist cards effects are disabled as well, so no minato or gaara card can help u in arena.

2. buff clearers (han, edo yugito, madara edo) only clear temporary buffs (lasts for x rounds). in your situation, fire main's ninjutsu urge is a universal buff (wont go away at well when he's alive), therefore it wont be cleared. same as scales (kushina's, roshi's, iruka Y+1 passive, etc...) buff clearers wont clear scales.

assist cards effects arent buff, so they wont be cleared, but to point it out again to you, all assist cards effects are disabled in arena.