Thanks to the huge damage stat, Isaac can easily reach Boss Rush if reached in time. But while Boss Rush can provide extremely beneficial items, most bosses won't die in a single hit (and damage cannot be increased to one-shot them), resulting in Isaac having to avoid several attacks to fire the next tear. It may be better to skip the Boss Rush to avoid taking unnecessary damage.
Luring enemies into the bouncing tear may be a viable strategy, especially if it is stuck somewhere.
Purposely making the tear stuck (e.g. by shooting it against a wall directly, making it bounce back and forth) might be viable situationally (e.g. Larry Jr. or any fight, where the boss is stationary, especially when this stationary enemy is in the center of the room.
Shoop Da Whoop! is a valuable item since its damage scales with Isaac's damage, one-shotting most bosses.
Bob's Rotten Head is also a very strong item because the poison effect deals triple Isaac's damage.
Rotten Baby's blue attack flies give Isaac a more consistent means of dealing damage.
Godhead will cover a large portion of the room with its damaging aura. When combined with another item like Ouroboros Worm that speeds up the tear, the entire room may be cleared immediately.
Maw of the Void can eliminate entire rooms in one go if the circle attack is charged.
The Boomerang will deal double Isaac's damage, for a total of 300 damage, and it recharges in 4 seconds.
Magic Fingers can clear rooms in one go, as it scales with Isaac's damage.
Magic Fingers no longer scales with the full damage, being fairly mediocre.
Toxic Shock allows Isaac to clear most rooms upon entering them, as it will deal double Isaac's damage (for 200 in total) to every enemy in the room upon entering.
Pupula Duplex Isaac's tears become a huge arc covering more than half of the width of a typical room allowing for an easy run while one-shotting bosses.
The Parasite Isaac's tears split into smaller ball-shaped tears upon hitting enemies, causing the room to quickly fill with bouncing tear shots that can quickly clear a room.
Sacred Heart and Spoon Bender grant homing, which causes Isaac's tears to hunt down nearby enemies or linger around bosses instead of ricocheting randomly. Telepathy for Dummies also provides the same benefit, albeit temporarily.
Spear of Destiny deals twice Isaac's damage per tick, defeating enemies and even bosses incredibly easily.
Sharp Key is very good since it scales with your damage and has no cool down. It will take about 6 keys to kill ??? with this Item.
Eye Drops allows you to stagger your shots, meaning you can fire more often and sometimes simply fire two shots at once.
Eye of the Occult allows you to control your tears making hitting enemies more reliable.
Notched Axe swings scale with your damage without any delay, making it a surprisingly good weapon.
Spirit Sword swings ignore tear delay, making the challenge a joke.
Circle of Protection is very effective, as its contact damage and deflected tears scale with Isaac's damage. This is especially useful for clearing stragglers.
Mom's Knife should be avoided; despite enormous damage, it will take a long time to charge for any meaningful distance, so Isaac will be essentially reduced to melee range.
Brimstone, Monstro's Lung and Tech X should also be avoided. Although the attack will probably be enough to destroy any enemy or boss, Isaac is defenseless during the lengthy charge time. Tech X also loses the benefit of bouncing attacks.
Ipecac should also be avoided. The tears will not bounce anymore, and due to the great height of the tears, these will pass over the enemies, being very difficult to hit.
Technology should also be avoided, as the delay between lasers will become very long, and the lasers do not bounce.
The Small Rock and Pentagram (if offered by a deal with the Devil) should be avoided; the former will only lower Isaac's speed while the latter will only result in a loss of a Heart container(s).
Proptosis Will lower damage as the tear travels, without any plus to damage.
Consolation Prize Since your lowest stat will, most likely, be Tear Delay and that stat is fixed, there will be no stat change. Will still drop coins/bombs/keys like normal.
Items that increase damage or tears won't affect Isaac's stats.
Items that adjust tear range will cause tears to be recalculated: more range means slower fire rate, and vice versa.