A battle system idea...but I think something is missing?

[Gregory2590]

Some ideas I jotted down in notepad an hour ago...But it feels like there's something crucial i'm missing. Any ideas? Comments welcome(read: needed) also, I didn't describe some of the support drive possibilities mainly because I still have to figure out HOW i'm going to work them.
-------Assist Battle system-----
1. Battle consists of 1 leader and 3 assists
2. Supports are onslaught defender and supporter
3. onslaught uses attack based moves defender protects leader supporter aids oher supports and leader
4. leader's stats on things change depending on the supports and character relations
5. game over if leader dies
6. Support drives can be activated after a certain usage of support moves
7. Types of support drive possibilities:

Attack x Attack x Attack = Enrage
Attack x Attack x Defend = 50% defense increase for onslaught supports for 5 turns
Attack x Attack x Support = Major attack boost on leader
Attack x Defend x Support = Increase all stats by 25% for 5 turns
Attack x Defend x Defend = Counter attack ANY damage done to the leader for the exact damage
Attack x Support x Support = Team combination attack. changes depending on leader.
Defend x Support x Defend = Invincible for 3 turns
Defend x Support x Support = Slight defense stat increase and invulnerable to status changes for 3 turns
Support x Support x Support = Completely heal party and casts a status effect on all enemies regardless of resistance except for death and silence
8. Support abilities:
Onslaught = Use offensive attacks/spells
Can follow up with leader in attacks
Increases leader's base attack slightly
Defender = Can be ordered to cover an attack at the cost of their hp
Can use a defensive spell on leader as a follow up
Can also be used to attract attention from monsters
Gives a slight defense boost to leader
Supporter = Can buff party and debuff enemies
Healing ability

9. Strengths and weaknesses:
Onslaught= Pros: Great attack
Great Agility
Cons: Worst Defense
Worst MP
Defender = Pros: Great Defense
Great HP
Cons: Worst Agility
Worst INT
Supporter= Pros: Great INT
Great MP
Cons: Worst attack
Worst HP