Pikmin 4 is forgiving, but a few habits separate a smooth run from a frustrating one.
The single biggest efficiency gain is learning to use Oatchi in parallel rather than as a reaction to a blocked route. Put him on Rush against an obstacle while you move a different squad somewhere else, then come back to the opened path. Treating Oatchi as a second player rather than a tool roughly halves the time spent standing still.
With a cap of three types in the field, Red plus a gate-solver plus a situational type is almost always correct. A common early mistake is loading Red, Yellow and Blue everywhere, which leaves no slot for Rock when a crystal wall appears - and no slot for Ice when you reach the Frozen Inferno route to the Ice Onion.
Sparklium is concentrated rather than evenly spread: Blossoming Arcadia holds roughly 1,500, Serene Shores around 4,000, and Hero's Hideaway around 7,000. Hero's Hideaway is also the area where you will need Rock Pikmin for crystal walls and, later, the Scorch Guard for the Ice Onion. It is the highest-value area in the game for a first sweep.
The Scorch Guard costs 50 Raw Materials for your character and 100 for Oatchi. The Frozen Inferno boss, Snowfake Fluttertail, is a fight you are significantly better suited to with Ice Pikmin on the field. Collect materials before you commit to the cave, and bring Ice Pikmin when you go in.
If you want online Dandori Battles, that is a Switch 2 Edition feature - along with the online leaderboards in Dandori Academy. On the base Switch release, Dandori Battles are local only, and the update's Relaxed and Fierce creature activity levels are the way to change difficulty rather than the ladder.
If a squad gets wiped, rewind rather than restarting the area. There is no day limit on main exploration, so there is no clock to protect by rushing. New players often treat a death like a Pikmin 3 mistake and restart from the last area, which costs far more time than a rewind ever would.
One of the most common criticisms of the release is the lack of navigation tools. There is no minimap and no fast travel marker. Learn the layout of each area by walking it, and use Oatchi's sniffing - not navigation - as your reminder that a castaway or treasure is nearby.
The Ancient Sirehound is a multi-phase fight that expects you to have used a wide range of types by the time you reach it. If you skipped the Rock, Ice or Winged routes on your first pass, go back and clear them before you attempt Cavern for a King. The final boss is the point of the type-gate system, not a check on your DPS.