A Plethora of Information and Sources to Indulge in:
Youtube Channels in Leagues (google the following and search for the GBA or UCL according to their involvement):
-Global Battling Association
-Shadypenguinn (GBA and UCL)
-aDrive (GBA and UCL)
Damage Calculator:
https://pokemonshowdown.com/damagecalc/
Pokemon Battle Simulator:
https://play.pokemonshowdown.com/
Smogon Tiers and Pokedex Information:
http://www.smogon.com/bw/articles/bw_tiers (a bit outdated, but helps understand the tiers!)
http://www.smogon.com/dex/xy/pokemon/
-Global Battling Association
-Shadypenguinn (GBA and UCL)
-aDrive (GBA and UCL)
Damage Calculator:
https://pokemonshowdown.com/damagecalc/
Pokemon Battle Simulator:
https://play.pokemonshowdown.com/
Smogon Tiers and Pokedex Information:
http://www.smogon.com/bw/articles/bw_tiers (a bit outdated, but helps understand the tiers!)
http://www.smogon.com/dex/xy/pokemon/