Tackle eligible requirement

[Exkalybr]

In a game I had last weekend, Team A was running an unbalanced line. 4 linemen to the left of the ball, and only a guard and tackle on the right. Is this a legal formation even when the tackle does NOT report eligible? Or is he eligible just because he is on the end of the line just like a TE? This was a youth game, so the numbering exceptions do not apply. I need to know if this is a legal formation or not. The visiting team coach of Team B said the formation was illegal. Was he right? Any help on this would be appreciated.