This strategy holds off the Leviathan Remnant's third attack stage, as long as possible in which it will punt you with its tentacle, destroy all cannons, and constantly send spike mines AND puss balls while you're trying to kill it.

This guide is for medium difficulty, As story and easy mode requires less hits and the potential to lose health by its attacks is less severe.

Try this method in in your first playthrough or in impossible mode as the most risk-free tactic.

For hard/impossible mode, know that you need to take one shot extra with the ADS cannon on each weak point (that is when you have destroyed the hard covering) (so that makes 7 shots for each weak point).

Also make sure you have a reasonably upgraded plasma cutter or contact beam with you, because on hard/impossible mode, the tentacle will probably destroy your last ADS. But if you have followed the routine, the weak point probably won't take many shots to be destroyed. Have fun!