Do ALL the other various remittance or money transfer services like Transferwise, Xoom,
Remitly etc also charge GST to transfer money to India, just like Money2India from ICICI bank does ?

Is this a rule from RBI or Government of India to charge GST on ALL incoming money transfers to Indian banks from abroad either by incoming wire tranafer or EFT?

The GST they charge is nominal, it's not on the entire amount, but a fraction of it. But it's still there.

Like If I transfer Rs. 100,000 i.e 1 Lac Rs to India from Canada to India via Money 2 India,
they will charge me something like Rs. 200 GST on it.

The GST goes up as the amount of transfer increases. Like if I transfer 5 Lac Rs. the GST on it is Rs. 550.

Not the GST is in addition to the money they make on the exchange rate.

So far I am getting good exchange rate with Money2India as I have a promotional offer of 40 paise extra than their normal rates, so I am OK with it. Just worried about the GST they charge.

Due to the promotional rate the exchange rate is on par with Transferwise, Xoom, Remitly, etc. But not sure if these guys also charge the GST or not as I have never transferred through them.