About Holder's work

I was really not sure where to put this question, so my apologies, if i made a thread on a wrong place...

I was wondering.

Holder has made side battlers and monsters that are lovely.

I talk about this incredible pixel artist:

http://animatedbattlers.wordpress.com/

He does give permission to be used as long as proper credits are given.

What i am aware is that some of his work is

"Based on XP RTP"

"Based on Final Fantasy" 

"Based on SOMETHING THAT IS COPYRIGHTED".

Question is:

Is it ok to use something that is based on something else, for a commercial game?

I mean, it might be based on Final Fantasy, like being inspired by it, but does this make it illegal to be used for commercial use?

Same goes for RTPS.

I own RPG maker VX Ace (Steam version). 

I do not own RPG Maker XP though. 

Some stuff are Based on XP RTP.

Is it ok to be used for a commercial product without owning RPG Maker XP?

Thanks for your time.

Welll normally If i remember this question go in rpg maker discussion (not sure )

but normally for a art to be copyrighted is need to have  a same character from a game or the same style of a other author but

Holder are not copyrighted he have a unique style is not because is similar to xp or final fantasy they are copyrighted

Is like you said kaduki also copyright but he have unique style just he decide to put in vx format

in simple if you take inspiration from a art is not copyright until you don't use a a base for make it (like you take a holder character and just edit him)

if is start from scratch is different~

but if you only take the format of holder but you do totally on scratch is not copyright you say : inspired from holder

I hope you understand what I said~

If "Based on XP" means it is an edit of an XP resource, you can only use it if you own a copy of XP.

Thanks Shaz, so i must be more sceptic about Based on Final Fantasy or Suikoden resources right?

Why don't you ask Holder?