The behemoth Algos tend to operate across all financial markets. You will have heard them mentioned in the GameStop mania of a few weeks back, and they are similarly active in futures and commodities (less so in cryptos but this is changing).
They have such huge capital at their disposal that positions running into the billions of $$ is an everyday occurrence. Of course the FX market is very deep and no one player can consistently move it, but having the ability to hold large positions for relatively short amounts of time is a massive advantage for these machine traders.
The underlying rules of all of the big players used to be very simple and unusually similar (because the same guys wrote the rules!) but the advent of machine learning has meant that the underlying strategies and risk management models have evolved. Nevertheless, do not be surprised if the underlying rules are very simple like MA (moving average) crossovers and overstretched RSIs.
These funds are so big, they can basically dictate what happens in many markets at least part of the time. They may not be able to boss USD/JPY around during the Tokyo session but they can pretty much boss everything else at that time of day. Similarly cable and EUR/USD might get a bit big for them during early European trade but the underlying math is so fast and so clever, its unusual for them to ever lose money.
The real risk for these Algos is when a fundamental shock occurs, when real money starts to run for the exits and when the machines efforts to keep the market corralled leaves them with significant exposure. As we know in all markets, its when the positions get really huge and ‘samey’ that the big big reversal moves occur.
So should you consider trading short-term in the FX market and taking on the Algos? In general I’d say No, unless you are the 0.1% trader who has developed an uncanny synchronicity with your chosen market instrument.