Gens 1-5: Just use one good pokemon and overlevel everything. The more pokemon you try to use, the harder you make the game.
Gens 6+: Have 1 main good pokemon and a variety of back ups to cover the type spread.
Global EXP share is much more interesting. Nice to see a team full of the newest gen pokemon without grinding forever rather than Charizard with Fire Blast, Fire Spine, Flamethrower, and Slash.
He/Them
"Am I a butterfly dreaming I'm a man... Or a bowling ball dreaming I'm a plate of sashimi? Never assume that what you see and feel is real!"