JSFiddle - React, Tailwind, and code Playground

HTML

<div id="screen">

<input id='mySearch' onkeyup='searchPokemon()' type='text' autocomplete="off">

<table id="pokemons-list">
    <thead>
        <tr>
            <th>NO</th>
            <th>Nom</th>
        </tr>
    </thead>
    <tbody>
        <!--In your case this is auto-generated-->
        <tr>
            <td>1</td><td>Name1</td>
        </tr>
        <tr>
            <td>2</td><td>Name2</td>
        </tr>
        <tr>
            <td>3</td><td>Name3</td>
        </tr>
        <tr>
            <td>4</td><td>Name4</td>
        </tr>
        <tr>
            <td>5</td><td>Name5</td>
        </tr>
    </tbody>
</table>

</div>

CSS

#screen {
    position: relative;
    z-index: 110;
    background-color: #fff;
    width: 255px;
    height: 70px;
    border-radius: 3px;
    border-style: solid;
    border-color: #494949;
    user-select: none;
    font-family: Zig;
    color: black;
    font-size: 12px;
    overflow-y: hidden;
}

#pokemons-list {
    margin-top: 3px;
    border-spacing: 0px;
    align-content: center;
    position: absolute;
    width: 100%;
}

th {
   text-align: left;
   padding-left: 20px;
} 

td {
    padding-right:15px;
    padding-left: 15px;
    justify-content: center;
    cursor: pointer;
}

#mySearch {
    border: 3px solid black;
    font-family: Zig;
    font-size: 12px;
    position: fixed;
    overflow: hidden;
}

JavaScript

var rows = document.getElementById("pokemons-list").children[1].children;
        var selectedRow = 0;
        document.body.onkeydown = function(e){
            
            /*for (var tr[i] of table) {
                rows--;
            }*/
    
            //Clear out old row's color
            rows[selectedRow].style.backgroundColor = "#FFFFFF";

            //Calculate new row
            if(e.keyCode == 38){
                selectedRow--;
            } else if(e.keyCode == 40){
                selectedRow++;
            } else if(e.keyCode == 13){
                Pokemon_ID = selectedRow + 1;
                alert('Pokemon_ID = ' + Pokemon_ID);
            }
            if(selectedRow >= rows.length){
                selectedRow = 0;
            } else if(selectedRow < 0){
                selectedRow = rows.length-1;
            }
            
            //Set new row's color
            rows[selectedRow].scrollIntoView();
            rows[selectedRow].style.backgroundColor = "dodgerblue";
        };