They should rotate out the bosses bi-monthly for Anomaly Interception. It gets boring fighting the same ones over and over again. Here's how I would do it
>Water - Land Eater (Replaces Mirror Container)
>Fire - Nihilister (Replaces Harvester)
>Iron - Material H (Replaces Kraken)
>Wind - Gluttony (Replaces Indivilia)
>Electric - Storm Bringer (Replaces Ultra)