Summary
The primary goal for players in any main seriesPokemongame is beating all the gym leaders on the way to becoming the champion of that region. All of these gym leaders are meant to be a serious challenge at that point in the run, and players normally can’t progress onto the next part of their journey until they have beaten the necessary gym leader.
Each gym leader in the game will get progressively more difficult as the game goes on, but some players will find later gyms easier than others based on the team they are using. However, there are alsogym leaders who do not pose an adequate challengedue to the team they are using. As such, some of these gym leaders require some upgrades to their respective teams.

Blaine isthe fire-typegym leader in Generation 1 and every remake of this era in the franchise. He is the seventh challenge for the player, although the team he uses does not suggest that. For starters, Blaine only has four Pokemon on his team. On top of that, two of these team members are first-form Pokemon. The two fully evolved team members are fine on their own, but can easily be taken out with a strong water type. This fact is even more egregious as the player has access to tons of water types in the sea surrounding Blaine’s gym on Cinnabar Island.
This choice of team seems odd because there are plenty of other fire types in Gen 1 Blaine could use. As the seventh gym leader, he should also have five Pokemon on his team. Perhaps a suitable upgrade for Blaine would be adding a Magmar or Ninetails to his team. He may also want to swap out one of his weaker Pokemon for a Weezing with flamethrower just so he isn’t completely swept aside by a few Surfs.

One of the biggest criticisms of the Johto region is that many of the gym leaders only use Pokemon from Generation 1. However, none of the gym leaders in the region exemplify this issue more than Chuck.
Chuck is the fourth gym leader in the Gen 2 games, and he only has access to a Primeape and a Poliwrath. While he can sometimes pose a threat if players are unprepared, it seems strange that he only has two Pokemon at this stage in the game. This is especially strange considering Hitmontop is a viable fighting typePokemon added in that generation. Just giving Chuck a Hitmontop would make him slightly more of a challenge, while also providing the game with more Gen 2 Pokemon representation.

Players will run into Flannery as the fourth gym leader in Gen 3. She is a fire-type user, whose Torkoal will leave players in a spot of trouble with its access to ground-type moves. Unfortunately, the other two Pokemon on her team leave a bit more to be desired.
These other two Pokemon consist of a couple of level 16 Slugma. While having repeated Pokemon on a team is normal for a gym leader, it feels as if this gym is missing out. She could at least replace one of these identical Pokemon with a Numel or Flareon for some more variation.

The eighth gym in the Generation 4 games is the electric trainer, Volkner. He does have a varied team that can test players at this point in the game, but only having four Pokemon does leave Volkner as a bit of a let-down.
His Octillery is a great choice to stop players from sweeping his team with a ground type. However, Volkner could still prevent this with a water type that also fits the electric type, like Lanturn. Also, it would help if Volkner had a fifth team member,such as Magnezone, Electivire, or even an Ampheros.

Out of all the gym leaders in Gen 8, the dark-type trainer, Piers, probably has the most type variety on his team. His Scrafty is part fighting, his Malamar is part Psychic, and Skuntank is part poison type. Even his ace Pokemon, Obstagoon, has the secondary normal type. This offers the player plenty to think about in a battle. However, as the seventh gym leader, Piers could still use some more team members.
The final gym in the Gen 8 games focuses on double battles, so it makes sense for this gym leader to have an even number of Pokemon. Therefore, it is up to Piers to have more than fourdark-type team membersto pose this kind of challenge. The newly introduced Thievul or Morpeko could fill this extra slot nicely.

In Gen 9, players can challenge the gyms in the region in any order they wish. However, the Pokemon in these teams never change level so Kofu is supposed to be tried as the fourth gym in the game. He is a water-type trainer who can sometimes be seen as a step down from the third gym leader, Iono. She is an electric-type trainer with four Pokemon on her team, one of which is a terrastalized Mismagius with no type weaknesses.
As such, it seems that Kofu could use a bit more power in his team to raise the stakes. This can easily be achieved by simply adding a bulky Dredknaw or Dondozo to his team.