the best strategy in any game of splatoon is to get as close to the enemy spawn as you can and take them down before they have a chance to reach the objective or colour the rest of the map. even if you splat like 2 enemies you end up creating a cushion that the rest of your team can use to push the objective further along.
if you let the fight all pool at the objective, whoever's left standing can immediately hop on it and get the advantage. going backward is easier than going forward.