How can my level 1 aron learn endeavor
Through breeding. The father must know endeavor. Here Is a link to all of the pokemon that can breed with him
Its an egg move, use this chart to find exact breeding for him.
Check here for a list of endeavor pokemon aron can breed with to get a egg move
breedin with a male swampert or mudkip that knows the moveif you don't have one check eggs group here (in the base) and choose the male pokemon that knows the move by leveling up if not make a chain breed
you could etheir breed it down or use a move tutor if you have heartgold/soulsilver