In Spanish, there are two grammatical genders:

masculine

feminine

For articles, these are represented as follows:

Definite Masculine Feminine
Singular el la
Plural los las
Indefinite Masculine Feminine
Singular un una
Plural unos unas

It seems that the most logical adaptation in this context for gender neutral forms would be as follows:

Neutral (d) Neutral (ind)
Singular le une
Plural les unes

Example: the teacher

el profesor / un profesor

la profesora / una profesora

le profesore / une profesore

Le and Les are however already used as indirect object pronouns. They are gender neutral in this context.

Example:

Yo le di la tarea.

I gave him/her/it/them (sg) the homework.

Yo les di la tarea.

I gave them (pl) the homework.


Adjectives are much easier, however, as there are already established gender neutral words. Traditionally, adjectives are given the following endings:

Masculine Feminine
Singular -o -a
Plural -os -as

Example:

Gabriela es baja / Marco es bajo

Gabriela is short / Marco is short

Gender neutral adjectives have the following endings: -e, -es.

Example:

Ustedes son inteligentes.