The ratio purely depends on the deck you're trying to run, theme decks tend to have more Pokémon, closely followed by energy and less trainers; they also usually revolve around 2 colors (plus colorless) of Pokémon.
For example, the Lunala theme deck contains 24 Pokémon, 20 basic energy and 16 trainers (the colors used are psychic and fire). These types of decks are specifically built to help new players learn the basic rules and that's fine (in fact the Clanging Thunder (Kommo-o) theme deck is so good right now it's even viable against some competitive decks).
The difference between this and competitive decks used in tournaments is that theme decks are slower to get set up and get momentum, so faster decks can get rid of your main threats before you even get set up (e.g The Lunala theme deck's main source of damage against competitive decks would be Beware and Lunala; both require evolution - Lunala has to evolve twice, although if you replace some of the less useful cards with copies of rare candy you don't even need Cosmoem), beware requires 3 colorless energy and its main use is to take out basic Pokémon (which are useful in TCG as there are less cards required to get set up), its attack does 60 to evolved Pokémon and 120 to basics, 3 energy for 60 is pretty bad but 3 energy for 120 is ok. It's also used for its ability that allows you to draw 3 cards when you evolve Stufle into Beware. 3 energy takes a long time to set up so I switched one of my fire energies for a double colorless.
Depending on one Pokémon only really works well if you have the trainers and abilities to be able to search the deck for the cards you want.
Most competitive decks I've seen contain a small number of Pokémon (like less than 12 total) even fewer energies (usually special energies) and a ton of trainers.
E.g a Gyrados deck I'm planning on building has 11 Pokémon, 4 energies, and 45 trainers. As stated before, the reason the trainers are there is to give me the ability to get the cards I want when I need them.
One thing to note though is that competitive decks are an expensive investment (the deck I'm planning on building is £117.41 approx and it's a budget deck, some cards are so high in demand they cost more, this deck contains Tapu-Lele GX which allows you to search your deck for a supporter - which is really good for a deck that contains a lot of supporters) so one copy costs nearly £40.
Theme decks tend to have more Pokémon and energies than trainers but are fairly even
Theme decks are great for beginners
Theme decks are slower to set up when played against competitive decks
Usually competitive decks are mostly trainers, with a small number of energies
Competitive decks with this ratio are a lot faster
Competitive decks are usually expensive due to many of the really good cards costing a lot of money for 1 copy
Competitive decks can contain other ratios if the strategy is vastly different to most of the others
Cards that allow you to search your deck or draw cards are really good for fast competitive decks when your main strategy is to do as much damage as possible (like the Gyrados which can do 240 easily once set up)