>>33342113Are you playing on Showdown or on-cartridge?
If you're playing on WiFi with the team you played through the game with, you will lose 99% of the time. To start with, either play on Pokémon Showdown using copy+pasted teams from team reports, or learn to use the QR Codes on the Global Link website to get teams for use on WiFi.
You'll probably still lose a lot, but look at your opponent and see what they're doing; if you find you can't hit their Celesteela because they have a Lightningrod user, that's not coincidence, that's their strategy. Learn from it. If you find you can't get an attack in because they're using speed controlling moves, that's not a coincidence, that's their strategy and you should learn from it.
When you see something you think is a good idea, consider trying it yourself, or think of ways to avoid losing to it next time.
Learning to get Pokémon in-game with good IVs and EVs is a bit of a grind, and I would recommend getting the hang of playing competitively on Showdown or with QR teams before you start trying to make your own Pokémon. There are a lot of places like WiFi general or dedicated VGC forums that are good for getting people's breeding leftovers too, which speeds up getting tournament-ready a lot.
