Garlic is an awesome companion plant, it accumulates sulfur, a naturally occurring fungicide which will help in the garden with disease prevention. Garlic also is helpful in pest suppression, it discourages aphids, flea beetle, Japanese beetle, fungus gnats, codling moths, cabbage loopers, ants, snails and spider mites as well as vampires and members of the opposite sex. There is also some proof that it deters mammalian herbivores such as rabbits and deer.
Plants to Avoid Planting with Garlic
It can be advantageously intermingled with most other vegetables and herbs, exceptions are asparagus , beans, peas, legumes, parsley and sage the sulfur it produces is detrimental to their development. 
Strawberries are sometimes suggested as a companion plant for Garlic and at other times the recommendation is to avoid intercropping the two. Although it is true that garlic discourages Aphids, spider mites and many other insects and accumulates natural fungicide it is not an ideal companion palnt for Strawberries.