What are the qualities, traits, etc for someone to play LB in youth leagues under 10 years old?

What exactly should they be able to do and what do they need to know?

Having coached youth football for a number of years, I find that my best linebackers are simply the most aggressive kids. Although some speed and size are helpful, the willingness to give and take contact is the key. This can be coached as this confidence can be developed. As the offensive schemes are fairly simple at that age, they can easily learn to react to the plays as they develop. At this age the best and fastest athlete should be at safety.

How to play fair, have heart, and know how to rap up and tackle. But most of all, they need to be able to know how to have fun!!!!

I agree with the answer above me but must be aggressive but not too aggressive to see the situation and react appropriately to it.
G

Nothing and nothing. Under 10 years old kids should rotate to every position that they are interested in for at least one half of one game. There is too much focus on learning a specific position too early in sports now.

Once kids reach 12 years and older then they should have a more defined position. In that case they should be able to understand how read what is happening in front of them so they can tell if it is a run or pass. They should know where they have to be on a given play. What their assignment is.

As for skills, LB's at 12 or so should be good at lateral movement, be able to run OK in pads, and understand the fundamentals of tackling.

I would like to give two thumbs up to the first answer. That is much better than my rant.

They should know how to make it rain

Power, speed, and the ability to fight through blocks and make great tackles! But as a LB, you have to be smart of where the ball carrier is going to be at all times!

they have to be able to hit hard, read the quarterbacks eyes, and and blitz

they should have a good time, like playing and show good sportsmanship, what else can you ask for out of a 10 year old boy. in the youth leagues there not going to make your son learn a play book or anything, there just gonna say tackle the guy with the ball.