What is the general rule for EU compensation?

For my flight, my colleague has managed to change it to another flight with suites.

But for sectors like DXB - KUL what kind of compensation are they giving?

There isn't a general rule, the rights are clearly spelt out under Regulation 261/2004

If an eligable flight is downgraded

a passenger is placed in a lower class than that for which a ticket was purchased, for a flight > 3500 km the airline must refund 75% of the cost of the ticket

Given that he was re-accommodated on the ex EU flight without a downgrade, no payout

For DXB-KUL sector, not being an ex-EU flight, the regulation has no standing

When I was referring to the EU regulation it was for the LHR and possibly other flights to/from Europe not the flights that I was booked/ticketed and subsequently downgraded.

For Emirates, flights to Europe are not covered by the act, so no EU compensation would be due

For flights from Europe, the downgrade entitlements are

30% of the cost of the ticket for flight < 1500 Km
50% of the cost of the ticket for flight 1500Km to 3500Km
75% of the cost of the ticket for flight > 3500Km