They would when suddenly every cards price shoots up due to inflation.
Team: Opp Support: -2 Opp Attack, Min 1
-8 attack against mono. Compare to Hugo. Would probably be banned.
Team: -2 Ability Minimum, Min 3
Does not affect bonuses. DRs, life drains, power/attack reducers, and pill thieves work slightly further. Would definitely be banned.
Team: Extra Mission Effort
Any card or ability specific mission (no room or clan win missions) gets one more point of progress when you do their tasks with this on the field. Probably avoid banning, but irrelevant.
Team: Support +2
This card functions as two clan-mates for support cards. So, this guy plus Oscar, Avola, and Moses: Avola can OHKO, Moses has -5 life, and Oscar sits at 10 power. Weakness being that it ONLY helps support cards, so your deck will either have some cards that gain no benefit from him or (full support) is vulnerable to SoA and thus, with exception of Rescue, has a useless Leader against GHEIST and Roots. If faced against the "Opp Support" guy, would give his ability the +2 too. Oh, so banned.
Opposite of Ashigaru. 8/8 stats with this being a negative ability. Legal, probably.
Steal Leader effect
Does nothing on it's own, but if your opponent has a Leader it disables that, and gives the effect to you. This Leader would have avarage stats.
Team:Courage or Confidence:+1 power and pill
In a round where either condition is met, your card has an extra power and gives +1 pill for victory. The condition would be shortened to CoC:... so it takes less space.
Team: Courage: Convert damage to life
In couragous turns you don't deal damage but gain life instead. Conversion takes place after all other damage modifiers.
Works really well with poisons, but not against them. Makes heal and +life/damage ineffective.
Team: Rainbow: Activate Bonus
If all your cards belong to a different clan their bonus gets activated and protected from SoB too.
This would promote rainbow decks, but they would still remain risky since you won't always draw this Leader.