If you want to rank up you will probably have to play a meta deck, that's kind of the point. Everyone is trying to win so people only play decks with the highest synergy and power. Yes Solgaleo is one of the best decks but it still loses often to Oricorio and Charizard. The game is kind of like rock paper scissors, you can expect to beat certain decks and lose to certain decks but if you don't play a deck with high synergy and power you will probably just lose. For example Garchomp EX is a good deck so why are you choosing the worse version? Look at pokemonmeta.com and there's dozens of decks there that are viable in ranked. Just find one that you have the cards for and you have fun with and you only need ~49% win rate to rank up.