Margin requirements will vary from broker to broker, all systems are day trade only, so you will assume day trading margin. Under highly volatile market conditions, many brokers e.g. Interactive Brokers, have been known the increase margin requirements considerably on very short notice, so all Users should take this into account (using the Position Sizing Bot, we would expect a decrease in the number of contracts being traded during a volatile period anyway which should alleviate most margin increase concerns).
Interactive Brokers Individual accounts day trading margin is very high:
1 Emini NQ: $17,723
1 Emini ES: $12,838
1 Emini YM: $9,598
TradeStation:
1 Emini NQ: $4,400
1 Emini ES: $3,300
1 Emini YM: $2,613
Under very rare circumstances, for a User not using the Position Sizing Bot and a fixed 1 Emini contract per trade, a day in which we have max 3 Correlated Long Positions across the three different markets can look like: 1 NQ, 2ES for Interactive Brokers you will need margin: $17,723 (NQ trades), $25,676 (ES  trades) = total $43,499 (we recommend $125k for 1 Emini trades in a day which should provide you with over $75k spare margin on a very rare day with 3 correlated positions).