skorpi
Just put Pokemon in your party and use Flash. See if any of them can use it. And Sceptile and Castform etc can use it. But I would recommend not putting it on Sceptile if you started with that because it can learn more moves that are MUCH better in battle (You can get it removed in Lilycove, Pokemon Emerald and maybe Ruby, Sapphire?)
In Generation I (Red, Blue, Green, Yellow) the Pokemon who can use Flash are:
Pikachu, Raichu, Clefairy, Clefable, Jigglypuff, Wigglytuff, Abra, Kadabra, Alakazam, Slowpoke, Slowbro, Drowzee, Hypno, Voltorb, Electrode, Chansey, Staryu, Starmie, Mr. Mime, Electabuzz, Jolteon, Porygon, Zapdos, Mewtwo, and Mew.
the bulbasaur evolutions beedrill pikachu raichu clefairy evolutions and jigglypuff evolutions oddish evolutions paras evolutions venonat evolutions meowth evolutions abra evolutions bellsprout evolutions slowpoke evolutions magnemite magneton drowzee evolutions voltorb evolutions exeggcute evolutions koffing evolutions chansey tangela staryu evolutions mr mime jynx jolteon porygon mew raikou entei victini. these pokemon can learn HM flash which can be obtained on route 2 when placing a pokemon that knows cut next to the small tree. you can get cut by beating diglett's cave (first level of chapter 4)
HM's are move's that a pokemon can only be taught. Pokemon are not able to learn an HM through leveling up or evolving. The HM must be acquired throughout the game and then a specific gym master must be defeated in order to use it outside of battle.
I use Raltz with Flash. Obviously there are many more, but that is one.
a light Pokemon like Pikachu or Electrike.... those types.
Pretty much every electric type can learn that also some normal types and psychic types some examples include: Mew, Mewtwo, Pikachu, Raichu, Pichu, Electrode, Electabuzz, Linoone.
nincada
Chinchou.
all the Pokemon on dimmond that can learn flash can still learn flash in the platinum game too
Most electric type Pokemon can learn flash.
In Pokemon diamond many Pokemon can learn flash for eg. Electric Pokemon such as Pachurisu Pichu and Luxray all (eveloutions) and yeah just experiment and see what can learn flash!
No wurmple can not learn flash
Most electric types can learn flash like voltorb and magnemite.
Any Pokemon that can learn a electric move
Paris can learn cut and flash
Zigzagoon cannot learn flash in ruby
to learn flash you should have pokiemon up to 10
blitzle... i think
The following Pokemon that you can easily get to learn Flash in Sapphire: Beautifly or Dustox Lotad or Lombre Oddish Gloom
Bellsprout.