I ordered up trump from the dealer of the opposing team and the same person said they were going alone and asked for their partners best card. Is that legal in the euchre rules?
If the player who fixes the trump suit believes it will be to his side's advantage to play without the help of his partner's cards, the player exercises this option by declaring "alone" distinctly at the time of making the trump. This player's partner then turns his cards face down and does not participate in the play.
The player, who chooses the trump suit, either by accepting the up-card's suit as trump, or by naming a different suit, is called the maker. Before the play of the hand begins, the maker may announce; "Alone", in which case the maker's partner places his hand facedown and does not participate in the play.
Note that both these Rule compilations do not include your House Rule of a card being passed from maker's partner to the maker.
First it depends what euchre you are playing such as railroad, bid euchre or sometimes by house rules. In regular euchre you don't ask for your partners best but you can go alone against if those are the house rules. A similar situation is if the opponent reneges on a lone hand the maker gets his lone hand( not the usual 2 ) otherwise people would just renege, but also if the maker reneges on his lone hand the other team gets 4 points. It states quite clearly who ever reneges the opposing team gets the 4 points this makes sense to me because the rules do not say if the dealers reneges so I would assume it means who ever renges on loan hand the other team gets the point.) Now on a go alone against its the team that gets at least 3 tricks that gets the 4 points, Remember these are house rules or different games of euchre not regular euchre but some may adopt these rules as house rules.