EVs and IVs - This is the only part of the guide that is important. If you are still confused about the EV spreads, just use the recommended spread from Smogon after you create the moveset (please don't use the example moveset, it's bad). If you aren't satisfied with the recommended spread, you can try experimenting with the EVs by dragging the circles until you gain a stat boost. IVs basically work the same way as they would do in other formats.
Rules and Clauses - You must follow the smogon clauses, in addition to the Dynamax Clause (you can't dynamax/gigantamax your Pokemon), and all Pokemon must be obtainable at Level 5 or below (you can't bring Kubfu into LC even though it's a first stage Pokemon because it can only be obtained at Level 10).
All the banned Pokemon include:
All the banned moves include:
All the banned abilities include:
Strategy - The only thing that is not recommended for beginners in LC is stall with how frail and non sturdy the metagame is, every other strategy is somewhat usable in LC.
Good Pokemon/How To Use - The LC Metagame currently hasn't stabilized yet after the DLC access (at least I think so, the viability list looks to be missing a bunch of Pokemon), but it seems that Mienfoo and Vullaby are good choices according to the viability list (Mienfoo because of fast fighting offense, Regenerator, Fake Out, Knock Off to get rid of Berry Juices and Eviolites, and Vullaby for bringing really bulky support in Defog, pivoting in U-turn, chipping things with Brave Bird, and getting rid of items with Knock Off, although Vullaby can do much more than that)
Other Important Things - I feel like Knock Off access and recovery are the two most important things in LC. Knock Off just provides so much utility and even Pokemon that don't use it offensively can use it effectively due to how some Pokemon really rely on items like Eviolite, Berry Juice, etc. Recovery is also important, which is found in the form of Berry Juice and Regenerator. Berry Juice can basically revive a Pokemon, as the low HP values of LC Pokemon makes Berry Juice restore a lot of HP. Regenerator is basically free HP for doing almost nothing, and with how common switching in LC is, you can get back a lot of health quickly without the opponent being able to punish you for doing this.
Hope this helped!