Does it simply mean to be the best battler? Does it mean having a true understanding of your Pokémon's inner potential? Does it just mean having a deep bond with your Pokémon? How would you define what being a Pokémon Master really is?
In the novels written by the anime's original head writer, Pokémon Trainers earner points by catching Pokémon, evolving them, winning battles, etc. Pokémon Trainers would have a rank based off of how many points they had, with Pokémon Master being the highest rank. My own person idea of what a Pokémon Master, though, is that its not really something that you can become. Its the idea of becoming the best you can be. Its a goal that can never be reached but will always be strived for as people try to become the best, but there is always room for improvement and there will always be someone better.
To me, becoming a Pokémon master means being the master of Pokémon... as in having the skills to be able to understand and unlock a Pokémon's potential.
A Pokémon Master would be sombody who has the complete love and respect of all of their Pokémon, treats them with compassion, and is great at battling and strategy to the point where they either are a champion of a region, or were in the past. They know all about every kind of Pokémon, including movepool, stats, typing, abilities, and more, and can handle them affectionately. Also, the Ultimate Pokémon Master will have caught (or evolved a Pokémon they have caught into) one of every Pokémon species's final form except for Legendaries and Mythicals. This is not necessary for the title, but just to be the best among those with said title.
Someone who is both strong and caring, and can bring out the best in both their Pokémon and themselves. They have to know the ins and outs of the battle strategies, as well as be versatile and know how get out of a pinch. They must also respect their opponent (unless said opponent is a jerk ), and be willing to teach others what they know.
I made a mistake before, when I said the point system was from the novels. It actually comes from The Electric Tale of Pikachu manga. I got them mixed up because their both obscure adaptations of the anime that do a lot of interesting world building.
https://www.fanfiction.net/s/12920091/1Death-and-Rebirth-of-the-Inspirer Rēad 1st çhapter of this story (not mīne, Įa dœsn't wrīte that bēaūtifully) and vü will knōw. Also, the dīalogŭe about what Pokémon Master is is by middle of çhapter, sō pātıence is nēēded.
My interpretation is that to become a Pokémon Master, you have to develop a deep understanding with many Pokémon, and fulfil whatever journey you set out to complete to the best of your abilities. Whether that happens through capture, training or battling depends on the trainer. Yeah, a bit of a loose definition, but I imagine the term is rather broad.
If you want to become one, you need to be able to know your Pokémon, how to win every battle, be able to win a League and understand their feelings. It’s to complete the bond between Trainer and Mon and use that to overcome the world.
A Pokémon master is someone who has an understanding of all Pokémon. He or she can utilize any Pokémon to its fullest potetional, for the smallest Caterpire to the largest Steelix. The Pokémon master also has to have a starter to which they love and cherish. That Pokémon is their true best friend and either would lay their lives down for eachother.