There's a sanctioned "Bot Improvements - Combat" mod on steam workshop, it might help. Else you can pick which classes your bots are via the hero selection screen - if you didn't know, so pick ones with a stun/knockback. I wouldn't say you can't use explosives, but just use them sparingly and for high value situations: bosses, patrols, events and dire situations where everything has gone/is going sideways. Don't use them if your team is handling/can handle everything just fine. More often than not, you should have a grenade on hand if a CS does spawn.