So, how do you unlock better spinners?
Also I HATE the mission that unlocks Lana's Kokiri spear. HOW does one do it!?? Any advice?
The requirements for an A rank are as follows:
1200 enemy kills
Win < 15:00
Take less than 4000 (10 hearts) of damage overall
Spam your B combo. It's your only good move. If you see an officer charging up an attack, cancel out of your current animation with your dodge, and get behind the officer. When the weak-point gauge shows, break it.
Use your super attack sparingly, it has a long animation and doesn't hit a lot of enemies. You're graded on time so you need to get stuff done fast.
As soon as you hit around 1100 kills and can go into the enemy's base, drop everything and run over there. You should be able to get the last 100 kills in their base or on your way there easily.
Other General tips:
If you dodge and hold the button while holding a certain direction, you automatically go into a run. Upon going into a run, the only way to be interrupted is if you get hit, you attack, or stop. So, once you start running, you can release the dodge button and you'll stay in a run.
Materials and weapons will automatically be picked up at the end of the battle. No need to spend extra time running around the battlefield looking for loot you think you have missed.
Try not to pick up hearts, this will allow you to see how much damage you've sustained and whether or not you're still in contention for an A rank.