i dont think so man....cos as far as i no both guppies n bettas dont have the Labyrinth organ(an organ some fishes such as bettas and gouramis posess which acts like a lung and can take oxygen straight from the air)...so i dont think it wud b a gud idea keeping them in a bowl wfout aeration....n also(trust me...iv learnt from expirience)...its not gud to put an air rock in a bowl....current is too strong...unless u can find a weaker source of aeration....my first fishes wer 3 neon tetras in a 2 1/2 gallon fish bowl....all 3 died in 3-4 days time...da best fish to keep in bowls r bettas man...dey just refuse to die man haha...n also u shud tell us how big ur bowl in...in my bowl i had 1 male betta and 2 gouramis....dey did very well....now moved them to a 15 gallon tank...if ur starting out in da hobby i suggest u invest in atleast 15 galloner...go jalan pasar man...not very expensive...80 bucks can get tank wf filter all...good luck!!

PS : guppies n neon tetras arent da best fish for beginners....esp in a fish bowl...strongly suggest u get a betta