It isn't always easy to stand up for others in your alliance. When your nation isn't doing well, you might think, "What can I do?" when asked to help your allies. Here's a list of things you CAN do:
Trade! Tech and actual trading will benefit both of your nations.
Offer support! If you can't help with fighting or by sending troops, just cheer them on in the fight and make sure they know they have a friend.
Referral links! Ask for someone's referral link and put it in your signature on other