Dropping the "ga" particle

[VeritasKhan]

My understanding is that the "ga" particle can be dropped in casual speech if it (the "ga" particle) can be inferred from the sentence's word order or context/situation.

Would it sound normal/natural to drop "ga" from these sentences?

Situation　1:
Your boss picked you (Tony is your name) to go on a business trip. Later that day, someone asks your friend, "Who will go?" (dare ga iku?). Your friend says:

トニが行く。　Tony (ga) iku. - Tony will go.
(verb ending)


Situation 2:
There is a table full of food. You want to tell your friend that the sushi in particular is delicious.

寿司が美味しい。 - sushi (ga) oishii. - The sushi is delicious.
(i-adjective ending)


Situation 3:
At a party, your friend warns you about another guest by saying:

あいつが病気。　- aitsu (ga) byouki. - That person over there is sick.
(noun ending)


Situation 4:
At a party, your friend warns you about another guest by saying:

あいつが警官。　- aitsu (ga) keikan. - That person over there is a policeman.
(noun ending)


Thanks!

[RadioKid]

1) "GA" can be omitted. but native Japanese will say "Tony DAYO:It's Tony!".

2) "GA" can be omitted. but "SUSHI" is too vague. Native will say "ANO SUSHI, OISHIIYO!: That SUSHI is delicious!"

3) "GA" cn be omitted. "AITSU, BYOKI DANE: He is queer fish".

4) "GA" can be omitted. "AITSU, KEIKAN DAZE:He is police man".