Discussion approved.

Your idea is good, but, don't force the horse to drink the water, you can only take it to the source. Hope you got what I intent to say.

+1 !!
there are some things which can't be spoonfed. Riding is one of those! U can teach all the conventional things, but what about the panic situations?

Once he has learnt the basic riding techniques, it will be good if you can bring him to some biker meets. It will not only teach him that wearing helmet and other riding gear is 'cool' and he will be tempted to be a part of a clan of 'cool' guys and will take proud in wearing the helmet/other riding gear rather than taking it as something forced upon him.

If he has a generous spill on your ZMR, the repairs would cost well above 20K, so just to keep things safe for both you and your brother, its better you get him a second hand bike to practice on, and advice him to watch alot of youtube videos on how to ride a motorcycle.

OT.
Im 19 currently and the first bike I ever owned and rode was a Karizma and that too just out of the showroom, had close to NIL experience that time and the only resource I had was youtube, so in short, If I can do it, then so can your brother.

Frankly speaking Karizma ZMR shouldn't be difficult to learn on if ur bro knows to ride a cycle or an Activa.
I myself learnt on my Pulsar 220 and an Avenger.
You should first give him a theory lecture on how hardly any throttle is enough to get the bike forward, clutch has to be left slowly etc etc which u would now become more of an instinct for you.
Better to learn on an open ground where he hurts nobody and even if the bike falls nothing much happens.

I'm sorry, I didn't put myself forth properly.

My brother has approached me to learn the bike. So it's not spoon feeding like the last time I tried. It's been 6 years since that day

The thing is, when I learnt how to ride it was for fun, it was to experience what riding a bike is. Its was exhilarating and one of those moments you never forget in life and cherish.
I got a bike at 17, a second hand pulsar and rode it without a license and even rode it to the RTO to give my road test and came back. I took a bike for absolutely no reason and no necessity. School was a Rs.2 bus trip or a Rs.10(min) auto trip. I loved my bike.

But my brother wants to learn it out of need. He doesn't look at biking as anything more than a commute and a bike as a commuting machine. He is going to have a proper learners licence, proper gear- I am getting him another helmet and some gloves, He wants a leather jacket too but I have told him to wait for it. His learners license is due to come tomorrow and he has shown interest in learning from my bike but is very apprehensive about its size. I want to know how to instill confidence in him to try a bike that is much powerful, much heavier, has harder double disk brakes and is more expensive than the last bike that scared him. I am more worried about him, sure a fall would set my bike repairs north but I don't want him hurt. Also this bike will be his after he gets his license, which is why I decided to teach him on this itself.

he is currently also taking car driving classes and I am sure he is pretty fine at it by now.

Should I ask my parents to buy a second hand splendor or another 125cc?

Any further suggestions?

Thanks for the replies. I appreciate the help.

In simpler words, I do not know how to teach him :| (forget the bike and technical part)

Will try the youtube videos for now. I never thought of that.