Rattata is one of those Pokemon that is just plain cool. It is a little energetic rat that made a name for itself as one of the most fun gimmicks of early DP, the F.E.A.R. set (which stands for Focus Sash, Endeavor, (Quick) Attack, Rattata). Since then it hasn't seen as much love, especially considering how much better the Clefairy line is at that set. However, this lack of love is unfounded as Rattata has some tricks up those little purple sleeves. Rattata has an excellent ability and some nice Egg moves, enabling it to help out teams that need a bit more fun, while still getting the job done.
Sadly for Rattata, it is almost entirely outclassed in almost all areas by other Pokemon; however, in every case it has some quirk that makes sure it isn't totally left behind, sometimes even being a better choice than the more popular and well-known option. Taillow, Stunky, and Munchlax better move over, Rattata is in the building.
Rattata makes a decent revenge killer thanks to its access to STAB priority in addition to access to Sucker Punch. There are obviously other Pokemon that look better on paper, but none of them have the added ability to take on some Steel-types, which Rattata can do with Flame Wheel. This point in itself is enough reason to consider Rattata for a place on your team.Team Options & Additional Comments >>>
At first glance it seems like Rattata would be completely outclassed by Teddiursa and Taillow as a status sweeper. However, it has a higher Attack stat than Quick Feet Teddiursa after Guts, and also has a few quirks that give it the edge over the other Pokemon you might be considering to fill this role on your team.
The Normal / Dark combination is a staple on many Normal-type Little Cup sweepers such as Munchlax and Eevee, and Rattata is no exception to the rule. With access to a very good STAB in the form of Facade, Sucker Punch, and extra coverage moves, Rattata is a Pokemon to fear.Team Options & Additional Comments >>>
Most of Rattata's best options have already been mentioned. Rattata has a fairly extensive special movepool but for the most part Rattata's poor Special Attack stat of 25 is too low to be useful. Blizzard or Ice Beam is the only move with a possibility of being useful to hit Gligar switching in; however, that is a gimmick at best. On the physical side, Rattata can fill a offensive support role with Taunt and Super Fang to mess with walls, but again there are better Pokemon for the job in almost every case.
You may wish to run either Pluck or Zen Headbutt. Both are situational but can prove useful. Pluck can steal the opponent's pinch or Oran Berries if you are lucky. Zen Headbutt is Rattata's strongest move against Koffing, and is also a good option to hit the common Fighting-type priority abuse Pokemon switching in, notably Croagunk, for larger amounts of damage. Rattata is infamous for its F.E.A.R. set in higher tiers and can attempt to pull off such a set in LC. Reliable priority in the form of Quick Attack makes such a set possible for the more ballsy battlers that play Little Cup. Another gimmick set it can run is one consisting of Substitute + Pinch Berry + Reversal. Another point to note is that any set you do decide to use can run Facade. A lot of teams run Will-O-Wisp, and abusing that fact with Guts is always a good way to make the best of a bad situation.
Checks and Counters
Rock-types have been mentioned as problems for Rattata. Good choices include Onix, Rhyhorn, Geodude, Omanyte, and even Nosepass. All of them have high Defense and are resistant to Rattata's STAB. Rattata has paper defenses so any strong attack from any one of them will ruin it. Other walls that give Rattata a hard time include Gligar, Koffing, and Shellder. Gligar can set up and sweep, Koffing can wall Rattata but needs to be careful not to give it a free Guts boost with Will-O-Wisp, and Shellder and easily take Rattata out with a Choice Scarf STAB move. Rattata also won't like taking Fighting-type priority attacks from the likes of Croagunk or Riolu either. Any strong and faster priority will suffice, as it is likely that Rattata will have taken previous damage through either recoil or status, making Elekid and Dratini good choices as well.