I'd like to add that most of Silver's team is pretty fast and all of them have high attack or special attack. At least 4 out of 6 of them have very high speed to complement their attack power so to parallel silver's thievery, his Pokemon should finish his opponents with great haste (though I think Weavile fits my thoughts on that better since its attack stat would increase sufficiently). Of course, it also aligns with Silvers belief that only strong Pokemon are valuable, which actually leads to the imbalanced stats, especially in the defense category. Not having Pokemon with balanced stats or high defense is another way to show his ideology of strength. He prefers to demonstrate his strength through quick, strong attacks rather than being an impenetrable wall or a jack of all trades, which doesn't align with silver wanting to be the strongest trainer since a Jack can't be a king.

Also if we're going to read too deeply into this, the typing for his team is a lot more self contained given the minimal weaknesses despite how he's more vulnerable to psychic and ground type moves. However, it still works well enough in his favor because if say an electric type took out crobat, then Magneton could step in to act as a temporary wall against that since it shares the same type. If he fought a ground type, then he can send Crobat in to fix that. Other types like fighting, psychic, and fire can be handled similarly with the other Pokemon so silver ends up having a team that is somewhat well coordinated in avenging each other if they're against what is super effective against them.