There is one glitch i foun a few years ago
go into celedon dept store
talk to the girl hos thirsty 50-100 times ( did that cuz i was bored)
she'll say leave me alone andpush you away*
go outside and keep going down untill the dept store is out of site and the girl will come appoligize to you and give you a itme call mo'h go to cinnibar and talk to the guy who wanted your raichu he will say here i will give the pokemoin you gave me and you give me that mo'h** say yes and he will give you a kotea(glitched item al a fossil)take it to the guy who resurects foddils and he will say oh this rare fossil i need a few minutes for work.(or something like that) and leave the building and come in for 25 times and go to the guy he will say fossil unkown you have? say yes and he gives you a pokemon its random i did it every time i started new game the pokemon he gives are mewtwo,kabuto,dragonite,ho-oh(YES HO-OH!!!***),chansey or mew.
Notes:*:You should not havegave her a drink for the first time
**:You should have traded a raichu to him
***:Ho-oh is the least likely one you get and he does come Also he was in the first episode so they must have thought to put him in a glitch. his moves are fire blast, flamethrower and peck