The first, second, is better if you say only : siempre cepillo mis dientes, nunca lloro.. more short and you can understand that you are talking about yourself..

Cojo la pelota.. i think cojo is only used in spain.. for Latinoamérica it would be : agarro la pelota.

Guardo mis juegos it's fine.

No quepo mis ropas i don't understand. That you can't fit in your clothes? 

Caigo bajo las escaleras.

Vosotros is another word only used in spain.. for us it would be.. les doy una cerveza.

Estoy un León i don't understand.. I'm what context..

Hago una maratón.. compito en una maratón.. participo de una maratón..

Pongo la olla en la mesa it's perfect.

No sè perfect.. No lo sé.

Salgo el tren en mi parada.. I can't understand 

Traigo una canasta para el picnic..perfect.

Veo tu madre no.. veo a tu madre.

Hi.

1-well both sentences are correct if you say "yo siempre cepillo mis dientes" it's OK but sometimes (sometimes) we don't use the pronoun "I" (yo) so if you want you jut can say "siempre cepillo mis dientes" and automatically we know that you're talking about you. But both sentence are correct. 

2- Yo nunca lloro and nunca lloro are correct. 

3- in Spain they use "coger" (to take) it's correct. But in Mexico we say "tomar" "agarrar" (to take). Are also correct. 

4- correct.

5- "No me cabe mi  ropa" or just "no me queda mi ropa" 

6- "me caí de las escaleras" " I fell down upstairs " 

If u need help let me know :) 

Sorry, I have been at work for the past week! Thank you for your help on the responses

No quepo mis ropas i don't understand. That you can't fit in your clothes?

    Yes; as in I have gotten too fat and cannot fit into my clothes anymore

Estoy un León i don't understand.. I'm what context..

    Saying that I am a lion, as a metaphor 

Salgo el tren en mi parada.. I can't understand

    I am trying to say I leave the train at my stop