The best Pokémon Go tracking and radar apps for Android
Pikachu forest in Tokyo, Japan
PokéMapper-Pokemon Go Live Map
Get this one while it's still at the Play Store. Arguably the best free Pokemon tracker, PokéMapper offers a variety of critter filters, notifications and directions. It will even list Pokestops around you and say if they are expired or can be shaken for loot, plus it shows gyms around you with their prestige levels and strongest guard Pokemons. The downsides: it takes forever to scan and load all the circles in the hexagonal plotting that the app builds around you, but if you are patient, you will be rewarded handsomely.
PokiiMap
This one's also not in the Play Store, and we'd advise against using your main account to login, though it's hard to resist, as the app lets you tap on the Pokemon it finds around you directly and launch a Poke Ball barrage against them. Initial scanning is pretty slow, not unlike most other crowdsourced apps, but once you are aware of your surrounding, you can preview a list of what is where, how much time is left on the Pokemon before they expire, and the distance to the target. Heck, PokiiMap will even fire up Google Maps and give you directions to the Pokemon of your choosing, as well as notifications when they have spawned nearby.
PokeRadar
Next one of the APK kind, PokeRadar might not have the interface of the previous too, as it is essentially just a map of reported or predicted spawning Pokemons based on previous reports, but it is a no-hassle app that doesn't require that you log in with a spoof account, plus placing reported Pokemons is very easy, with all of them just a scroll away at the bottom of the screen. Bonus: you can tap for directions to the desired beast directly from PokeRadar.
PokéLIVE
This one you won't find at the Play Store, but it is no less well-made than PokéMapper, with beautiful visuals that let you tell when a Pidgey is a Pidgey (it looks like Ecans in PokéMapper), locations and expiration time for the Pokemon around you. It's more cumbersome to set up, as it requires a faux Trainer account to work well, but the app guides you how to set it up best, and you can filter the critters, too.
Things that are NOT allowed: