I figure this may have been mentioned before, but I couldn't find it. Can we have a setting where only elders and above in clans can request for troops? It could be turned off and on so its not mandatory. It would help against clan hoppers that are solely joining to fill their castle and leave. Once the members join and actually contribute by donating and talking in the clan chat can they request for troops back. the troops that hoppers donate (if they even do) are usually useless. I don't think clans could abuse this feature to get free donations without giving back since the troops they get aren't strong
but a much simpler answer is for sc to stop new clan members requesting in the first hour. there would be no point hoppng then as if u stay in a clan u can request every 30 mins minimum.